Step 1: Install and run this iPod Transfer
First connect your iPod to your computer and open your iTunes. Then run iPod Transfer. After done, all the playlists and other files will be shown on iPod transfer below. Prepare to put songs from iPod to iTunes.

Step 2: Select songs to transfer to iTunes
From this library, you can now select and mark the files you want to transfer songs from iPod to iTunes.

Step 3: Click Export to iTunes
Click the "Export" button and start to put songs from iPod to iTunes right now. Choose "Export to iTunes" and OK, the software will synchronously transfer your songs to your iTunes quickly.

When the transferring finished, a window will pop up. It shows that how many files have been done. You can click the Yes button to view the output files.

Related Guide: How to Transfer iTunes from One Computer to Another?