click the top of the load switch and the drawer will open. place a CD in the tray and click at the top again. the drawer should close, the elevator will cycle, and the drawer will open again and let you add another. this is how a Nak CD player 2 works. Let's hope yours is similar.
To remove individual CD's, highlight the disc number you wanna change and click at the bottom of the load switch. replace the CD and click at the bottom again.
try it and let me know if it works.