Software management with Gentoo Linux is quite easy because it provides a special tool called "Portage".
Portage itself makes use of "Ebuild" scripts to compile and install applications. Gentoo's Portage handbook tells you all about it. For software which is not in the official Portage tree, you can setup a so-called "Portage overlay". There's a nice tutorial for working with overlays using Layman.
Apart from that, it's possible to manually copy the ebuilds you desire to your local overlay folder and set up your own Portage overlay. Check the comprehensive Howto for details.
More stuff is coming sooner or later...