1. open "Skin" -> "Bind Skin" (option box) and try to change settings...

2. my guess is that the join at the elbow is not at the correct position... so that the skelleton at this point isn´t bind...

so try this tutorial... but first of all I´d do the free dog tutorial from simply maya.... there you leran the basics of NURBS modelling

Dave K´s Head moddeling...

If you need some human characters, there are some in the download area of simply maya of try the free dog tutorial in the video training section. There are the basic of modeling characters with...