You say the turntable has twin "phono" jacks? (I assume you mean RCA.) Get a cable which will take that to 3.5 mm stereo and plug it into line-in, or plug it into a small amp, and from there to line-in.
Alternatively, just bit-torrent download the tracks you legitimately own. I was capturing my favorite tracks, turntable to amp to line-in to Audacity. My son challenged me: "can you capture a track faster than I can bit-torrent it?" It wasn't close.