Suzy is right
However, how you handle this loss is dependent on your situation. Here is the guide
http://www.irs.gov/pub/irs-mssp/pal.pdf
To get a quick overview, google "passive activity loss"
But for now, until you get an accountant or finish your education, there are three dates you need to consider
1. The date on which you decide to make your unit a rental. this is either when you bought it (if you bought a property to be used as a rental) or when you moved out (which sounds like your case). You need a value of the property on this date. Any simple appraisal will do. You can even do it yourself by taking comparable sales in your area.
2. The date when the property is available for rent. This is frequently the same as the first date but can be later if you had some improvements you needed to do before it was available. You may need to prove this date in an audit. The most reliable way is to place a "For Rent" ad on a dated medium (even Craigslist) and copy it for your records.
3. The date a tenant moves in.
Keep records and receipts of everything you do regarding this rental. Keep track of every trip by car, note the date, miles, and purpose.
I suggest getting a book.. Go to a book store and start reading on rental income and taxes and see which book fits your style. Verify or clarify the information with
Internal Revenue Service