The SteamOS installation process is fairly streamlined, but not as simple as installing a Windows programme.
At the very least, you should know how to change the boot priority in the Bios. More importantly, you should be prepared to spend time browsing the official SteamOS discussion forums for answers.
Here are the minimum hardware requirements from Valve:
Intel or AMD 64-bit processor;
At least 4GB of RAM;
250GB hard disk space or more, 1TB for Default installation;
Nvidia, AMD, or Intel graphics card; and
USB port or DVD drive.
You should prepare a USB flash drive with at least 4GB of free space. This drive must be formatted using the FAT32 file system. If you are using the Default installation method, name the USB drive "SYSRESTORE" during the format.
There are currently three methods of installing SteamOS.
Do note that the first two methods described here will erase all data on the computer's hard drive. You should also back up your data before trying the third dual-boot method, because selecting the wrong option (and ignoring the warnings) will delete all the data.
The first two methods require a motherboard that supports UEFI (Unified Extensible Firmware Interface). This is an improved version of the BIOS that initiates the boot-up process on PCs before the operating system takes over. This technology is used by Windows 8, so PCs that are less than three years old should be UEFI-capable.
Even if your system is not UEFI-ready, you can still install SteamOS using Method 3.