Your post is a bit confusing - you are trying to burn a music cd of multiple songs, yes? Here is a more detailed explanation of how to use ExpressBurn:
Open the Express Burn window and select the 'Audio CD' button.
You can 'open' indivdual songs (or folders) - or - drag the individual files (tracks) from their source folder into the program main window, in the order you would like them to play.
You can rearrange the play order by dragging each track in the window (play order is top to bottom.)
Once you have all the tracks you want (up to 79:59 minutes) and they are in the order you wish, then select the 'Burn Audio CD' at the bottom. This will open the 'Burn Audio CD' dialog box.
This is where you can choose 'Finalize Disc', and Burn Session At Once to customize pause (the silence between tracks.) 2 seconds is fairly standard for a cd.
best of luck - hope this helps.
(ps. to be clear - it doesn't seem like you need to be using WavePad to accomplish what you are trying to do)