What the property/building is used for doesn't matter. You own it, and someone else pays you so that someone else can use it. What they pay you is rent, any way you look at it. The income gets reported on SCH E as a part of your personal tax return.
You "WILL" have more questions if you've never dealt with rental property before. Feel free to ask them here. While I already know what a majority of your questions will be, I'll wait for you to ask them. Otherwise, the "information overload" all in one shot has the tendency to overwhelm a first time landlord.
