Hi Mrs. Newbiecpl2008,
Rest assured I'm not exactly svelte myself and neither is my hubby, but that has not been a problem for us. We've found most men prefer curvy women, and tend not to care so much about stretch marks or cellulite. Your attitude is what's really important, and it sounds like you'll do just fine.
As far as where/how to go about that first experience? Keep reading here, and talking with your hubby. Share the board with him, and talk some more. Eventually the right situation (for you) will present itself.
In the meantime,
=)