I don't want to sound elitist, but this is really the level of thing you need to do yourself. If you can't do this, you won't be able to properly maintain your box (at the very least keeping up with updates), and then it will become a security risk and impact the rest of us.
There are many good tutorials on this sort of stuff, and Linode's library is a great learning resource:
http://library.linode.com/
The "Using linux", "beginners guide", and "getting started" sections are probably the most relevant here.
If you don't have time to learn, a VPS might not be for you; shared hosting may be more appropriate, because at that point somebody else takes care of all the technical stuff.