basic wall texture

greetings. i am moving along with my bathroom remodel. i have had to replace some drywall. how do i get the same texture on the walls as in the rest of my bathroom. the bathroom is rather large. This is a builders grade level house that was built about 8 years ago. the wall texture is nothing fancy...looks like it possible could have been rolled on even. i have seen a method where you get the consistency of the compound more liquidy and use a paint roller to put it on? will this method work? any recommmendations? can i do this over painted drywall for a uniform look?