ZBrushCentral

Want to add more poly's to a mesh to make it longer but ZModeler is not cooperating!

So with Dynamics getting more and more popular I’m in the process of trying to simplify some meshes and weld others. I hit a wall as a fantasy head gear thing I made is a double sided piece and so I got rid of that and kept the center of the mesh (which is a single sided piece) as well as the accessories for it but what I need to do in ZModeler is just add some poly’s. I can’t seem to do that. I’ve tried Edges and Faces and all I get is extrudes, which just makes everything double sided, which I DO NOT WANT. So using ZModeler is there a tutorial out there that will show me how to go about doing this correctly? If not I’ll use Silo but it’s been a while since I’ve used that program but there I KNOW I can do what I need to do but I’d prefer to do it in ZBrush.

Thanks!
Richard