Adjusting Bottom Edge of Curtains

Draw a rectangle in the desiderata size of your curtains and apply one of Rosies Drapes and Blinds presets. Merge all. Go to Effect/Distort/Creative Transform. When dialog box opens scroll down Templates and select ripple (5th one): . In the right side you will see the settings - change them to ones on right.

Point your cursor in the middle of darker fold at the edge of curtain as shown and click, if you hold button of your mouse process will go on and you will make ripple too big. It will take some practice. Do the same with all folds. Now we will have something like shown on right.

Now pick the smudge template (second one) , set Range to 27 and Level to 20. Straighten your curtain folds in directions as shown. You can get a very realistic effect playing with these tools. Click ok. Then you will need to use Magic Wand tool to take your curtains out of the background.