libXm.so is the system X-Windows Motif library. I don't believe we distribute this package in ISIS and therefore it must be installed by your System Administrator. You may want to post which operating system you are using so others can give you some hints on how to install the library if you self-administer your computer.
Also, IDL is a visualization package. We do not distribute IDL as it must be purchased throught Research Systems Inc. When you purchase IDL they provide documentation which describes how to use it.