@skye you sew a straight stitch along the sides of the legs, but you don't hem them or add the waistband yet.

Then, you take an iron and you press the seams kinda "open" so that you don't have the little flappy tab, and everything lays flat. (Picture two pieces of fabric, both folded in half on their own. Then move them so that the 'folds' are kinda facing each other, fold-on-fold with a little microscopic gap between them. It's in that kind of orientation.) Then, you might sew over it again with a serger a using a zigzag stitch (if your machine has it).

Then, you hem and sew on your waistband.

Hopefully this makes sense. A phrase people sometimes use is 'press the seams flat'.

It's a bit more work. I usually don't do this, but it's up to you if it's worth it to you! :)