How to make the mesh "bend" (screenshot included to show problem)

Support Animation and Rigging
1

Hello blender artists,
I’m having trouble getting my rigged mesh to “bend,” it instead does this when I rotated a bone:

ThubEWP.png1599×899 251 KB

Help please? Sorry I’m in a rush, I’ll be back later to post any additional info if required.
Thanks!
-Zac

2

You need the geometry in the arm to enable it to bend

Screen Shot 2014-02-15 at 21.07.18.jpg1024×339 73.2 KB

3

Thank you so much, really appreciate it.