Use CDex with Lame for .mp3. Your ears can thank me later.
CDex - http://www.free-codecs.com/download/CDex.htm
Newer editions of Lame than is available bundled with CDex - http://www.free-codecs.com/Lame_Encoder_download.htm
If you insist on using WMP, put the disc you want to rip in the drive, then on left side pane, click the album. Check off the songs you want to rip or the top box for all songs. The rip button will then be enabled (it is greyed out before) near the top middle.