What do I do if I forgot to file my taxes last year? Can I file them with this years taxes?

No - you must report 2006 income on a 2006 Form 1040 - you cannot combine 2006 and 2007 into a single filing. It's never to late too file - I suggest that you complete and send in your 2006 income tax ASAP. If you owe the IRS money they will charge you interest for late payment, and also a penalty for late filing, but the sooner you do it the less those charges will be. If they owe you money, it's in your best interest to file and get your refund. Do not wait!

Ebaines is correct!

Also, if you are entitled to a refund for 2006, the IRS will pay YOU interest, so the refund will be slightly higher than the figure on your tax return.