Just above your question, to the right, is a button marked "Health Pages". Click on it and you will find many topics with links that explain thyroid disease and thyroid function.
You are a "4"? I suppose that means your TSH is 4.0, which is a little high, indicating that one or more of your thyroid hormones is a little low. Normal TSH should be somewhere between 0.8 and 1.8, and 4.0 indicates mild hypothyroidism.
Ask your dr for a copy of your lab results so you will know your numbers. Then post them, lots of people are really knowledgeable and will help you