Hello Paula - you shouldn't need to add anything to a compost heap if you have the right balance of soft, wet and hard,dry material, air, water and time.
Getting a compost heap to cook is a bit of a skill that you learn in the same way that you learn to cook in the kitchen. Some cakes turn out well, others not.
I find that everyday kitchen waste such as cauliflower leaves, grass cuttings and so on add enough water, chipped branches from shrubs add enough "fibre" and old envelopes (seethrough windows removed) and other bits of paper add cellulose to help. I have an open heap which I cover with a large sheet of plastic to keep the slugs and snails in place and I just add a bit every day and wait.
If it is very lucky, I might add a bit of horse or sheep dropping to it, as and when a passing animal leaves a bit at my gate. Other than that, I just leave it alone and it works.