Welcome bro. okay, this is some kind of basic explanation that u need to know about custom kernel and root. rooting is something about installing an app called Superuser as there are some apps required superuser running on your phone. one thing i found very useful is if you root your phone, you can do lots of things easily like you can simply do a backup for your apps data using Titanium Backup, which cannot be used if you dont have root in your phone.

As for rooting, you can get it by simply flash a custom kernel like Speedmod Kernel (available for froyo and gingerbread roms, but froyo is the stable one.Go to the first page to find the link and also read the whole thing on how to root when you already with the kernel.)

IMO, i don't think rooting can actually brick the phone. we're not the same like in iOS where if you do something wrong during Jailbreaking, you'll bricked your phone. The 3 things i can say that can make brick your phone is:

1) During flashing process, you suddenly mess up during the halfway of the process then the installation is not complete. ( for me, i think this is the most dangerous one and have the highest risk that can kill your phone straightaway.)
2) Flash custom firmware without unlagfix your phone.
r3) Flash without checking either your 3-button recovery is enabled or not. if you have a wrong flash and your 3 button recovery is not working, you know the answer.

Take some time to read and understand about your phone first. First page really have a lots of good information for new starter. 

flash a stock kernel will not root. only custom kernel will. flash custom kernel is the best ,safe (if you follow the instruction properly) and simply way to get root.