Hello I need help when I boot from my windows server 2008 cd it just starts up with a black screen with a blinking _ in the left upper corner
Please tell me what I can do

Is the BIOS set to boot from Optical drive ?

It is set to the optical dříve Yes

Well the blinking cursor indicates that the disc is NOT bootable.

Normally you would get a "press any key to boot from CD" message.

Where did the disc come from ?
Also is the optical drive correct as the newer discs from MS are DVD not CD's..

It's a cd I made myself by mounting an .iso file to the cd so I don't know what's wrong

Sounds like the ISO burn failed.
Check the CD to ensure it has unpacked the ISO image correctly.

I'd start over.

I checked and yes all the files is the BTW the cd is a lumatron cd and when I'm coming home I will check if it's a cd or a dvd

Can I make a bootable usb?

Assuming the hardware supports it, yes.

What was the original source of these files you're mounting via an .iso?

I got my .iso file from a windows server 2008 install disk

An original install disk?

I am not implying it was pirated but want to cut that option out of the equation?

Its my friend who got it and he lives long away from me, and no its not pirated but can I split the iso file to 2 cd's? And how