I'm getting a gameinfo.txt error, whats wrong?
You put the jbmod folder in the wrong directory, place the jbmod folder in the 'half-life 2' directory, not the 'hl2' directory.
Also make sure you have 'use folder names' CHECKED when you are extracting.
There is also a bug related to using a desktop icon to launch JBMod. It appears to happen if you have any spaces in the path to JBMod (for example: c:\games\steam\SteamApps\SourceMods\JBMod is fine, but c:\program files\valve\..etc.. throws an error because of the space in "program files". For the time being, just launch JBMod from Steam.