How to write to your government representative?

I was browsing online recently on how to write a letter to a government representative. From what I have seen, the letter should consist of 3 paragraphs but I can't find the site that actually said what each paragraph should say. Does anyone know?

I don't know what sort of site would tell you such rubbish.

Tell the rep the full details of your situation/problem and what you would like him or her to do about it. There is no formula.