ok, the lava texture and the jungle pack generally come in a folder or contain a readme. It tells you what folder you ahve to extract it to. This is important due to the .vmt settings.
You need to extract to a folder specified in the .vmt under:
C:\Program FIles\Steam\Steamapps\<Your Steam Username>\Team fortress 2\tf\materials\<vmt folder specification>\
It'll be under the... $baseTexture operand.
The jungle pack, I'm certain it contains a readme to installation, as it contains models.