IPhoto is now asking which library to open.

Trying to open iPhoto. Out of the blue, it asks which library do I want to open. Library? Never dealt with a "library." Haven't downloaded anything, and no updates installed lately.
I don't have any photo software installed. It says select form list (blank of course) or create one. What will it take to simply view pics in iPhoto? Could I have malware?

Start iPhoto while holding down the Alt key.
This will open up a small dialog where you can either choose to select an existing library or to create a new one.