1998 Honda Civic Squealing Noise

I recently bought a used 1998 Honda Civic DX. As of a couple days ago, a squealing noise started coming from under the hood. The noise only starts after the car has been driven for a few minutes, and only when my foot is NOT on the gas. Whether I'm slowing down, sitting in park, or just cruising, I can still hear a loud, high-pitched squealing noise. It seems to be coming from some belt or another to the right of the engine. Should I be worried? Is there something easy that I can replace myself to fix the problem? Any help is appreciated!

Thanks,
Adam Schwartz