Installing VMware vSphere Hypervisor AKA ESXi 5.0 is not such a hard task however you need to make sure your server is compatible with ESXi I 5.0.
To check that go to the VMware Compatibility website and check If your hardware can run ESXI.
If all OK, Go to the Download page and download ESXi (you will need a logon account).
The ESXi installation takes 10 minutes.
Once you download the ISO image and burned it, Insert it to the server and boot from it.
Press Enter to start the installer.
Accept License agreement.
Select install drive
Select Keyboard Layout
Set root password
Press F11 to start install
Press Enter to Rebot
All done, remove media let ESXI server start.
After the server boots, go to the URL in the ESXi screen and download the VMware Client software to manage you host.