If you are looking for an idiots guide, install Ubuntu.
Seriously, if you are no proficient in Linux, then you should try something else. Gentoo is getting more complicated as time goes by IMHO, so if you do not know your way around Linux then it is not for you.
www.gentoo.org is the best place to start, the docs section is a verry good source for installing and configuring the basic system, and more specific parts like X. http://en.gentoo-wiki.com/ is the wiki site. They had major crash late last year, but working OK now.
a Google search will generally give a lot of the answers that you might be looking for.
Gentoo is not for the faint harted, it is for people that really want to learn the ins and outs of Linux. Emerge is probably (my opinion) the best package manager out there.