Download, install, and launch the Audacity recording software on your computer.
Connect the left and right output channels of the tape machine to the channel 1 and 2 inputs on the mixer, using the XLR cables.
Connect the master output of the mixer to the line-in jack on your computer, using the 1/4-inch to 1/8-inch adapter cable.
Mount the analog tape reel on the tape machine.
Turn on the power to the mixer, and move the Master Volume, Channel 1, and Channel 2 level faders (or knobs, depending on the mixer) up to 0 dB.
Press the record button in the Audacity recording software on your computer.
Press the play button on your tape machine.
When the tape has finished playing, press stop on the tape machine and in the Audacity recording software.
Apply any audio clean or desired effects to the track in Audacity.
Select 'Export as WAV' from the 'File' menu at the top of the screen. The exported track can now be added to iTunes, or burned to a CD.