Hi Niamia
It seems like you don’t have the geometry parented to the armature. (select the geo, then the armature and ctrl+P) If it is parented and its still not moving, then its not weighted. (when parenting use automatic weights at first to see if things are working)If its weighted and still not conforming to what your arm bones are doing, then there may not be enough geometry to bend like that.
If you still want to share your Blend file use Dropbox, Google Drive, or something similar.
