monitor problem

Alright I have a relly old computer I use at home that decided it can’t do all I need it to anymore. So I recently added a new sick of ram(128) and a eathernet card to replace my modem. They worked fine. I then added a old video card, dont ask how old i dont know.
Here’s The problem When I reconect everything and power up, The monitor will only go to the blue Hewlett-Packard screen. It did this before I added the card then it booded ran what it needed and launched windows. Can anyone assist me in figuring out why it wont go any further than the Hewlett-Packard screen?