Welcome back to Linux.
To install software, you can use yum, which is command line front end for the rpm command, or use the GUI add/remove software tool, which is a graphical front end for yum/rpm. Enter man yum
and man rpm
on the command line for more information.
As regards the wireless, from a terminal window run the command lspci
(assuming that it's a pci card; if it's a USB device, run lsusb
) and post the chipset here and someone should be able to help you. The chipset is more important than the brand.