How can I get my monitor to work?

I have gotten 2 monitors and they both do the same thing. They are blank screens with nothing at all on them and the power and buttons on the front continually flash. WHen the monitors are unplugged from computer they are fine, it's when I plug them in that they don't work. This is an old computer and is using windows 95. I believe it's a creative 32 drive.It is mainly used to write essays and do homework on, so I would like to try and salvage it. ANy help would be appreciated. Thank you