Compiling ? What/how ??

[swish]

The max level for my server is level 70. I wanted to make a quest that will give you a level each time you complete it up to level 75. Doing the quest is not the problem, but when I die passed level 71+ I lose all the levels down to level 70.
I was looking around about how to change features.h and I found out that I need to compile.
What is compile ? lol.. How do I do it ?

I would really appreciate if anyone can give me a link or an explanation on how to compile features.h.

Thanks alot =)