I'm trying to start up my old PC, what to do?

[LAPIII]

this is a Compaq PC that seems not to have an operating system. Once that I press the power button, there is a black screen that leads to a message that reads something about insert the disk. Is this the operating system, if so I can download onto a DVD a free operating system such as Solaris 10.

 

[Proximon]

You will need something a bit more compatible I think.

How about Ubuntu?
http://www.ubuntu.com/getubuntu

Edit:
Well, that screen asking for a disk could mean that the hard drive has failed. You might want to verify that it's working first.