Designing Inkscape Patterns for Backgrounds
To design Inkscape patterns for backgrounds, open Inkscape and create a new 40 x 40 canvas. You can change the size of your document by pressing <Ctrl><Shift>D simultaneously or by clicking File on the main menu and then accessing the Inkscape document properties option. You may even want to turn on your grids, but that option is up to you.
You should now have a nice 40 x 40 square area to use for your pattern.
Grab the pen (Bezier) tool and draw your pattern. For this particular pattern, start by drawing a triangle originating from the top left corner (coordinates 0,40) and 20 pixels down and twenty pixels to the right.
Go to the bottom right corner, move to the left 20 pixels and draw a diagonal from there to 0 pixels up the right side of your image. Bring your pen all the way to the upper right corner, back down to the lower right corner and then close the path at the point of origin. Your pattern should now look like the next image.
Select both of the shapes you just made by holding the Shift key down while clicking each with the selection tool. Combine them by clicking Path on the main menu and then choosing the Combine option.
Add color to your pattern. Select the object and click Object on the main menu, followed by Fill and Stroke. You may have to resize your window once the Fill and Stroke window opens.
Choose your fill color on the Fill tab and then turn off the stroke on the Stroke tab.
Save your work, because you have just created your first of many Inkscape patterns.