Sherry is right. The home study is nothing to worry about -- even though we all do!
Your social worker will probably want to know more about your family, your marriage, your philosophy on child rearing, etc. He or she will also walk through your home to ensure it is safe and appropriate for a child. You'll also need to gather financial documents (bank statements, credit card statements, loan balances, etc.), as well as a copy of last year's tax return.
It is very rare for a couple not to "pass" a home study, so just be yourself and try not to worry too much. It will all be fine! The home study is actually the easy part.
Good luck,