How to work with draft messages?

I was writing a lengthy e-mail this morning on my desktop computer. I saved it as a Draft and then took my iPad over to Starbucks where I wanted to proof the e-mail, add a little more text, and then send it. Now that I'm at Starbucks I can see the Draft message, but I see no way to continue editing it, or even sending it.

Is there a trick to working with Drafts?

If it matters, I'm a Google Apps user and syncing using the Microsoft Exchange feature. Besides this the e-mail experience on the iPad has been terrific.