There are a few baywindow tutorials on the web, and this is my version of making one.  Since I had never gotten around to making one, this was a real experiment for me.  I usually try to find ways to make things as easy as I can.  So I am going to try to make this painless, but it will involve a little math!  Another great version of making a baywindow can be found at Moonlight Designs.  If you want a double inset look to your panes, try Debbie's tutorial.

Things to keep in mind are to be sure and have your ruler up, name those layers, and follow the steps in order.  You can just use my sizes for the panes and avoid doing the math.  We will be using the Preset Shapes tool, the Draw tool, the Deform tool, Pattern Fill and Inner Bevel to create the window.

You will need to pick a wood fill ahead of time and leave it open for a Pattern Fill.  You can find wood images in the room tutorials.  Large pieces of wood are here, and the smaller pieces of wood are here.  Be sure that if you pick a larger wood image to either resize it or select a piece out of the larger image.  You don't want to work with too large of a wood image for the fill.  I used this wood image, and you can just right click and save it if you want to use it too.

Create a new, transparent image, 600x300.  Name that first blank layer background.  We are going to create the outside frame first, so add a new layer named frame.  Turn on your ruler if you don't have it on already.

Click on the Preset Shapes Tool.  Use the rectangle, size 10, antialias.  Start your rectangle not on 0/0 but on 5/5.  At the bottom of your PSP window bar, it should say 290, 590 as your ending point.

You now have the solid color frame.  Click on it with the magic wand.  While it is selected, click on your Fill tool.  Make sure you have your wood pattern open.  Choose it as the Pattern Fill and fill your frame line.

Leave the line selected.  Go to Image/Effects/Inner Bevel.  Choose the Frame Preset.  Say ok.  The outside of your baywindow frame is now done.

Add a new layer and name it left pane.  Use your selection tool to draw just inside of the upper left of the outside frame.  You can choose any width you want for your sides, my selection is drawn just under 150.   You have to visualize that you will be having a right pane too, and both these panes will be deformed to extend the perception of moving outward.  So you don't want them to end up taking up so much room that your center pane area will not be large enough.

Then copy this selected area on your left pane layer and paste as a new image.  We are going to create our left pane on this new image.  Click on your Shapes tool again.  Once again start your beginning point at 5/5.  My selected piece was 133x279.  My ending point is 10 less than that, or 123x269.  Select the line with the wand.  Once again flood fill with the Pattern and then go to Image/Effects/Inner Bevel with the same Frame preset.

You are ready to add your lines in the pane, so add a new layer to this new image called lines.  Here is where a little math comes in.  I want 1 vertical line and 2 horizontal lines.  First the vertical.  Half of 133 is 166.5.  So don't sweat it and choose 166 as the midpoint.  Click on the Draw tool.  Choose Single Line/Stroked/Width 5/Antialias.  Put the point of the tool right on 166 and draw straight down.  Now for the two horizontal lines.  My height is 279.  One-third of that is 93.  My first horizontal line is at 93.  My second one is at double that, or 186.

Now use the magic wand to select these lines, flood fill with the Pattern Fill and then do the Inner Bevel, same Frame preset.  Do NOT merge these two layers yet.  Move the lines to the bottom layer.  This puts them under the outside of the pane.  Now merge visible layers.  Save this file as window pane.

Copy it and paste it onto your window image as a new selection onto the already named left pane layer.  It should fit right in exactly.  If not, you'll be able to correct this with the Deformation tool when you use it to deform the pane.  See how snug it looks?

With the left pane layer active, click on the Deformation tool.  The deform lines and boxes will come up on your left pane.  Hold down the Ctrl key on the keyboard.  Move the mouse to either the top right corner or the bottom right corner.  Now squeeze inward.  Look at the screen capture to get an idea of how much to move that right side in.  When you have it the way you want it, release the mouse and the Ctrl key.  You can then click on another tool such as the selection tool.  A window will pop up asking if you want to Apply Deformation?  Say yes.

You now have the left side done, so copy and paste as a new layer.  Name it right pane and Mirror that layer.

Note on the screen capture that I have actually left a little space between the frame and the right pane.  I'll be explaining that a little later.  Add a new layer and call it center pane.  Go back to the Shapes Tool and draw your rectangle between the left and the right pane on this new layer.  You may need to zoom in after this and use the deform tool to make sure it fits just right.

Copy this layer and paste as a new image.  You are going to do about the same thing that you did with the left pane.  Click on the black lines, pattern flood fill and then use the Inner Bevel.  Add a new layer for the lines.  Click on your Draw tool with the same settings as before.   Again a little math is needed.  My image is 311x217.  This time I want 2 vertical lines and 2 horizontal lines.  I divide 311 by 3 and get 104 rounded off.  So my first vertical line is at 104.  My second vertical line is at 208.  For the horizontal lines, I divide 217 by 3.  I get 72 rounded off.  My first line is at 72, my second at 144.  Select these lines with the magic wand and flood fill with the wood pattern.  While still selected use the Inner Bevel with the same settings.  DO NOT merge these two layers!