There are many more seasoned individuals out there than myself, but my best suggestion is to dive in, don't be afraid to learn, and, also, don't be afraid of trashing your system. The first thing with Linux is to learn some basic commands in the terminal.
Sabayon is primarily a KDE distribution, though you can install GNOME if you wish... that's up to you. Each are different in their own regards and really its up to the user to decide. Stick with the defaults for now. The commands in the wiki are strictly for the terminal, so open up konsole -- should be in the favorites section of the menu bar, and follow them closely. Your first step should be to enter root user mode. type:
then enter the root password (you set this up at the time of installation).
I do recommend you become somewhat familar with portage, the package-manager that Sabayon and Gentoo employ. This is primarily what the first set of commands do. They query the server for a set of packages or applications, download and compile them on your machine. it may look intimidating, but try the commands out and see if your wi-fi works. Again, don't be afraid. The worst case scenario is a clean re-install, but I'm guessing you don't have a lot of critical data stored on that partition yet, so it shouldn't be a hastle.