Hi and welcome to Just Answer! I'm happy to help answer your Finance questions. Feel free to interject at any time if you need clarification.
Do you have your W2s from your jobs for the past 5 years?
Is the $600 a month your partner receives Social Security?
Okay, you will need to start with the first year that you haven't filed. Summarize the receipts/transactions on you bank statement, whether it is using an Excel spreadsheet or even just a pad of paper. Get a total for each category for the year - total insurance, total gas, total office supplies, etc.
Do this for each year and then you will be ready to either take the summarized information to a tax preparer or prepare the returns yourself.
You can access prior year forms at this link if you will be preparing them yourself: http://www.irs.gov/formspubs/article/0,,id=98339,00.html