How can I make easy DIY curtains?

I think you'll love this project, Michele:

https://www.hometalk.com/diy/living-room/curtains/5-curtains-10113567

You can use a flat sheet, opening the hem. However, you can probably purchase them as cheaply as you can make simple ones.

Use flat sheets. You can buy clips at Target that have the curtain rod circle on the. Find the right length and fold the sheet over at the point. Clip on the curtain rod clips and insert a curtain rod. Done.

I get a piece of fabric, fold over 1/4 inch across the bottom of my curtain size piece and then fold again, press it well. Then do the same at the top, but do 1/4 inch and then 3-4 inches. This will make a pocket for the curtain rod.

Flat sheets or fabric! You can buy clips that hold the curtain, so there's no need to have holes in the curtain. I did this in my boys' playroom. I used iron-on fusible patches to make a nice edge on the bottom (I don't sew). So Simple!