One of my favorite things to do. Search the Net for my favorite audio tracks. Thanks to the Motion Picture Experts Group for developing such a convenient format of encoding audio data. Despite its limitations, it has endured for almost 20 years.
I use is WinAmp to play MP3 files, even though the player is no longer supported.
Now to encode sound in MP3 format you need an encoder program. MP3 encoder software developers are currently oppressed because the technology is patented, but there are a few which find holes in the system. They only put out the source code of their software to public, you need a compiler to actually make it become software. One of such encoders is LAME (stands for LAME Ain't an MP3 Encoder); here is LAME v3.93 Win32 Installer (610K). This encoder allows you to set output bitrate, input and output sampling rate, perform high-pass or low-pass filtering on encoding, and more. Personally, I find that GPSYCHO psychoacoustic model used in version 3.93 and before of LAME provides superior quality for constant and medium bit rates, as the newer versions (using nspsytune) are mostly tuned for variable bit rates.
Since the big guy Napster has gone belly up, one of the ways to get the MP3 files you need is peer to peer networks, big ones being Gnutella and Soulseek. Good old way of scouting web searches, FTP sites and IRC works too, but is much more time consuming, and lately, more and more Web sites host music.
My track list that's been here previously is about 10 years out of date now, so it's been scrapped. From time to time I show up on Soulseek (where I also use the name of Pa3PyX) and make my tracks available for download. Most of my stuff is electronic dance music, particularly synthpop, eurodance, progressive house, vocal trance, and happy hardcore. Rock is mostly limited to softies, power ballads, progressive metal, glam, and pop punk.