I've been using Nicotine+ as my Soulseek client and it's been working great for me.

I had an old mp3 player so I took that music and used it as my first set of shareable files. It took some time but I have been able to build up my library.

Once you're on soulseek, look for joaquim_149. A lot of it is lossless audio but there's also some mp3 files.