Linux never minds which kind of OS on ur computer. It has ability to manage other OS with strong GRUB utility. There r so many distro in the market in which popular distro like, SuSE; Red Hat; Debian; CentOS; Mandivira; Fedora and names r lot. Simply, collect any Linux distro, which u feel comfortable to operate (u can dnld from net as free like: OpenSuSE; Fedora; etc) either by ISO format / bit-torrent. Then write it to a DVD and then put inside the DVD-Rom following switch on ur computer. Now providing here step by step guide (www.dedoimedo.com/computers/opensuse-install.html) for a popular Linux OS. Just follow this guide and hope u will do the task successfully. This is just for an example.

i would suggest downloading the iso of your preference and instead of burning it onto a cd place it on a usb drive. The usb drive will read faster and better than any cd plus you will not have to hear those weird noises that come from optical drives.