Hi Artsuhtaraz:
That's easy!
Load your first song into WAVEPAD.
From the EDIT menu, select "Insert File..."
then from the little teeny window that opens to the right of "Insert File..." select "End".
An "Open Audio Files" window will open.
Pick out your second tune.
Repeat the above 4 steps (starting with "From the EDIT menu") until all your tunes have been added.
From the FILE menu, select "Save File As..."
A "Save Audio File As" window will open.
Give your combined file a new name, and click SAVE.
(Note: You can also elect to save your new file in another format at this point. WAVEPAD will default to WAV file, but if you open the "Save as type" dropdown, you can pick MP3 if you want.)
You're done!
Jerry