You may want to try it out on some scrap drywall and see if that is the look you want. The joint compund will need to be thined with water to make it easier to work start with and about 6 onces per gallon.

There also is a mesh roller(GOOP LOOP) that is used to apply a texture to the walls that you may to try out also.

The professional approach is to spray apply textures to achieve orange peel, knock down and other effects. If you already own an air compressor, its a no brainer, buy a texture sprayer and hopper. If you don't have a compressor, buy the pump applicator sold by Homax. They are available in the paint department at the box home improvement stores:

http://www.homaxproducts.com/catalog/textureguns.html

Hand applied texture using drywall compound is messy, very heavy texture, and will not give the results you hope for. Spray applied texture can be removed fairly easily before it dries if you don't like the results.