The first thing you see, when you start up your computer is the BIOS screen
The BIOS (Basic Input/Output System) is a small program running in the background and usually the only time you ever notice, that it's there is during start up. The BIOS enables and controls the communication between your hardware and your operating system.
Maybe you noticed a command in the BIOS screen during start up saying "hit DEL if you want to run SETUP"
If you don't know much about computers don't try and make any changes to your BIOS settings! If you make any wrong settings it can keep your computer from working right or even at all!
So....just enjoy looking at the black BIOS screen while you wait for your computer to start up (or go make yourself some coffee!) and leave any changes to the BIOS to the professionals / the technicians. Believe me - I DO!