1. Open Window Media Player 10 and for our testing purpose add any two songs to your Now Playing List.
2. Click the Select Now Playing options button under Now Playing and point to Enhancements, and then select Crossfading and Auto Volume Leveling as shown in the screen shot below.
Alternatively you can access Crossfading and Auto Volume Leveling option from Enhancements under View Menu
3. Now, from the Crossfading and Auto Volume Leveling Enhancement pane that appears just above the player controls, click the Turn on Crossfading link and move the slider below that to adjust the time(secs) of overlap.
That’s it!! Now, your music files will be playing using the amount of crossfading you have chosen which you can check with the tracks you have added to your Now Playing list.