I don't want to sound rude, but I think that you should head to http://wiki.maemo.org and reads everything from "beginners" section, first. It doesn't look like installing kernels and cssu-thumb is good thing to do for you, yet - you're risking getting unbootable phone, which will require reflashing (=losing some things, that you haven't probably, backup'ed).

After reading beginners section, you should be safe to use CSSU-Stable. Then, reading opening post of kernel-power thread (I'm not giving direct link on purpose - you should be able to find it via either wiki, or TMO), may get you ready for non-vanilla kernels (if, and only if, you'll completely understand what you have been reading about).

If everything succeed up to that point, come back to cssu-thumb and read opening post (again, most of the times, useful info is in first post of thread that interest you). After understanding it, you should be safe to go.

Sorry, if it sounds too bothersome - this device and it's tweaks are for people that like to gain real experience and skills, not just for "one-click install, and everything works on it's own".

cheers and good luck,
/Estel