Hello Leatherface,

first of all: TSP and the normal rating cannot be set. It can only be gained.
In order to do so, you will have to play on a server supporting it. This is done through ET 3.00 servers that support TSP rating by setting some settings and whitelisting TB's IPs for a port on their server. More to that here.

TSP had been introduced to show a clearer image of the skill base of players, rather than just calculating the rating by the amount of XP someone gained. More to that here.

Of course, to keep your TSP rating, just like with your normal rating, you would need to stay active and rate at least once every three days.

If there's more questions, don't hesitate to ask.

P.S.: You can filter for servers supporting TSP on our serverlist (server options tab).

/JoNny