What he means is just like i do
i have a local testserver on my local machine here at home.
I have installed easyphp to it, and from there i can install software i want to test, like SMF and TP for instanse.
Install SMF (the version you have running live) then install TP to that on your testserver.
Then open your livesite through Cpanel or FTp, download settings.php and settings.bak.php to a folder so you know where you have them.
Then upload and overwrite all the files from your testinstall on your local server to your live forum.
When all the files are up there, upload the two settings.php and settings.bak.php to your live site again.
Then point your browser to install.php (for SMF upgrade) and when that is done, point your browser to manual_tp_install.php and that will update the DB for TP.