I Need Help

I feel a little embarrassed to even write this. But I know that you all can help me. I've been an Active Rain member since December.  I've posted a couple of blogs.  I've read countless posts by others.  But I still don't know how to use "tags" and I'm not sure I even know they are.  I think they are supposed to help increase the number of readers my blog gets? Thanks in advance for your assistance.