Purchase a large bucket of premixed drywall joint compound from your local home improvement center, lumberyard or hardware store. (A 4 gallon pail will cost you about $15.) Also pick up a wide-bladed taping knife or straight-edged trowel (8 to 12 inches wide–—less than $10) for spreading a thin coat of the compound on the wall.
Remove everything from the walls including switch plates and receptacle covers. Clear furniture away from the wall to be textured and cover it. Spread drop cloths on the floor.
Strip any wallpaper before texturing. The high moisture content of the drywall compound can cause wallpaper to loosen–—and leave you with a time-consuming mess.
Start by edging all along the baseboard, corners and ceilings with a thin layer of the compound. About 1/8 of an inch is fine unless you want a very rough texture, in which case you will want to go thicker. You don’t have to be exact–—after all, a varied texture is what you’re looking for.
Cover only a small area at one time until you figure out how fast you can work. Drywall compound stays workable for a fairly long time, but don’t get carried away with how much area you try to cover at once.
Create texture in a wide assortment of ways: use old paintbrushes, wallpaper brushes or sponges to stroke or swirl texture on the wet surface; use your fingers to make all kind of designs; use stencils to apply pre-created designs. One fun idea is to have your children make hand prints and footprints in the wet surface. Anything goes.
Alternate between applying the compound and texturing it until the entire wall is covered.