Digital Scrapbooking Tutorial.
Cut a Curved Border.

This computer scrapbooking tutorial is for Photoshop but read through, you can probably do the steps in other programs.

Open a new document 3600 px X 3600 px at 300 resolution. Drag background paper onto the new document. Rename the layer 'Background.'

Drag a paper you want to use as the curved border onto the new document above the 'Background' layer. Rename the layer 'Curve.'

Select the pen tool. Set the pen to paths mode (the middle button from the pen options bar at the top of the page.)
With the Curve layer active, click your pen on the left side of the paper. Next, click your pen about halfway across the paper. Keep holding your mouse down and an adjustment bar will appear. (MAKE SURE YOU KEEP HOLDING the mouse button down until you are happy with your curve). Adjust this bar until your a curve is just right. Lengthen the bar for a larger curve or just a little for a smaller curve. Pull the bar up to direct the 'hump' of your curve down, down to push the 'hump' up. Dragging the bar right or left adjusts where the 'hump' is positioned.
Click on the right side of the paper to complete your curve. Hold the mouse button down to adjust this portion of the curve. When you are happy with your curves, click the pen on the right bottom corner outside your document, then click outside left bottom corner then click on you original starting point to complete your cutting path.
Open the paths palette (Window → Paths). Make your path an active selection by choosing the "load path as a selection " option. (3rd button from left on the bottom of the paths palette.) You should now have marching ants. Insure the marching ants go around the top of your paper. (If not chooses Select → Inverse)

With your Curve layer selected→hit delete and you have your curved border! Of course you can use this method to make a horizontal border as well.