Which web site are you referring to?
If it is charmm-gui, there is a forum for that here
, but most questions posted go unanswered lately, as they prefer that people use the Contact
page on the charmm-gui site.
Importing ligands which may or may not be be well defined in the CHARMM force fields can be an exercise fraught with peril. You should probably start with the CGenFF
site; there are some useful posts in the Parameter forum, and a paper or two.