I need help

I went a week ago to get a quad core Everything worked but it said unsupported CPU on screen, do I need a bios update if so will someone help me get it?

This is the Compaq website describing your (per filled specs) motherboard. Besides other things there is a list of supported CPUs. I did not find the BIOS update right away, but maybe you'll see it if you spend a bit more time on it. Alternatively, call their Customer Service.

The Sempron is an AM3 socket processor. Your motherboard has an AM2+ socket. While it is possible for an AM2+ socket to offer compatibility with an AM3 processor, the BIOS must support it. It doesn't appear that your motherboard will support the CPU you bought. You'll need to find a BIOS update that supports AM3 on that board (which I cannot find and am not sure exists), exchange the processor for an AM2+ CPU, or buy a different motherboard that supports the current AM3 CPU.