You layer the soil in--make sure it's damp, as too dry will dust out anyway--as you plant the strawberries in there. Fill to just below the first holes, and then put the strawberries in, firm down, and fill to just below the next level of holes, and so on. If you're still having trouble with the soil coming out, try ripping a "hole" to the center of a coffee filter, and putting one around each strawberry plant as you plant it (inside the pot) to keep the soil from coming out. They can be hard to keep damp enough in Colorado if the pot isn't glazed, so do be sure to water slowly so the water doesn't all run out the holes and some actually gets into the soil!