I can't solo on my guitar at ALL. What can I do to improve?

Well...I've done it. I finally started my own Heavy Metal band. Only problem? I'm playing lead guitar, and I can't solo worth a goddamned, and I've been playing guitar for almost 4 years now. Admittedly I've concentrated a lot harder on rhythm, especially improving my power chords and acoustic-ish stuff. But I suppose soloing is my "achille's heal". I feel completely...weak. I feel like a child who's learning how to read, and it doesn't feel good. I want to get better, but I'm embarred to go back to the beginning. What do I do? What do I learn? And how can I prevent these feelings of...being stupid?