The Source should link to a Github or Gitlab or whatever repository (or any other website that hosts and/or visualices the mod/texture pack's source in your browser)
The issue tracker is to send tickets and bug reports. Just leave the issue tracker blank...
Website is also optional, leave it blank if you don't have a website of your own that hosts or explains the mod aside from the CDB.
You probably want to leave all three of those blank, since this is a texture pack.