Firstly, I suggest backing up the whole site, including the database. then updating SMF to 1.1.7. This is more important than TP as there are security updates with the forum and TP 0.9.83 is stable enough.
I would then read some of the Documentation from TP's Doc site about the latest version, bearing in mind there are some known bugs, but as a whole, the current version is quite usable and offers many enhancements over earlier versions.
Note that TP does not currently work with SMF 2. As for Tech Head theme, TP 1.X.X no longer requires theme conversion and all SMF themes should now work with it, all that you need to do is add a Forum button to the main menu, details of adding a button can also be found at the Docs site.
Versions of TP prior to and including 0.9.83 need to be completely uninstalled from your site before attempting to install TP 1