Go to the Mixxx.org website, and follow the instructions to download it to your computer. Select "Save to Desktop," and a Mixxx icon will appear on your desktop.
Double-click the Mixxx icon to open the Mixxx program. At the bottom middle of your screen, find the library table section, which is similar in style and function to an iTunes library.
Select "Options" in the upper left-hand section of Mixxx, then in the drop-down menu, select "Record Mix." A new window will appear, prompting you to pick a name for your mix. Type in "MIX 1," then click "Save." You are now recording anything you do in the program.
Click on and drag a track from the library table to the upper-left section marked "Channel 1." Click and slide the crossfader lever located in the middle of your screen to the left, and press "Play." You should now hear the audio of this track either in your headphones or through your speaker system.
Continue dragging tracks from the library table to channels until you are comfortable with your mix and feel it is complete. Use the crossfader lever near the end of each song to move between the channels.
Press "Stop" on both channels and close the Mixxx program when you are finished mixing. Your recorded mix will be on your desktop labeled "MIX 1."