How do I make curtains from twin sheets?

Sew a pocket at one end to thread a rod through. Cut to length and sew a hem.

The easiest, no sew way is go install a curtain rod and use curtain clips. Just attach clips to sheets and hang up. Is that what you were looking for?

If you are wanting something simple, you can open the hem and run a rod through there. You can dress them up by adding trim. If you want it to ruffle run a stitch across the hem so there is just enough room for the rod to be fed through.

Many different ways to do it here's bunch of videos https://www.youtube.com/results?search_query=DIY+curtains+from+sheets+

I agree with all the above suggestions. Using sheets is a great way to make curtains, usually very cost effective for the amount of fabric yardage you get for the price.

For my sons room, I've personally opened the top hem (it's usually wider on the top) and have run the rod through that the same as Kathy suggested.

I've also used curtain clips like Naomie suggested in my living room, and cut the ends at window length and hemmed them.

here are ideas from hometalk

https://www.hometalk.com/search/posts?filter=sheets%20curtains