I need color correcting advice

I took these photos of a vinyl record jacket for archival purposes, and I included a white sheet of paper in the photos. I was wondering how I could use the sheet of paper, which is supposed to be white, as a reference and adjust the colors of the image so the paper appears perfectly white, which in turn makes the rest of the colors accurate.

I'm new to Photoshop, I'm taking a Photoshop college class but we haven't learned how to do this yet.