Oh, you've been there. It'd be easiest if you could actually share what is going on right on your screen, but how? Skitch is the answer. Importantly, it is FREE. Almost as importantly, it is EASY to use. You can grab screens, notate on them either with type or a drawing tool, and then use the images how you see fit. Simple. Go here to download (I would!): Skitch, you fool!
Then watch, quickly, how to use it. You'll never look back. Well, you might, but only to capture, notate and share. ;-)