I need to texture walls in a small bedroom. How do I do that?

There are additions to paint that can make the texture as you go. I did it once when I had a house with terrible walls. It was sort of like a sand that my paint dealer added when mixing my color. Instead of painting up and down, I kind of did a swirl and it looked so much better. If you texture the walls first, with some kind of texture compound, you will have to use a very thick napped roller to get the paint to cover. Suggest you talk to whom ever you buy your paint from.

You can buy texture in a spray can. Spray light coat over walls and roll finish coat over it.

texture spray can is cheap and easy. Available at home depot

Texture in a can is not cheap, you can rent the equipment to spray from Home Depot, but personally I would have a contractor do it. You can texture your walls without the sprayer. I borrowed a "mop" from a contractor and did a knock down by applying several square feet and knocking down with a trowel. Easy to do but will tire you out!

Wall paper. Yes, really.

I called a drywaller.