I think you are wondering about the little black rivets.
If you are wondering how to deal with the black plastic rivets, you are not alone.
I managed to bust one, then I looked in the manual, or asked
about it here, and I learned how to deal with them.
TO RELEASE A RIVET
Use a strong slender piece of plastic, such as the refill of a cheap ball-point pen.
Push the center of the rivet until it depresses a few millimeters. If the first
rivet resists you too much because some fool spilled Coca-Cola on it, then
go to another rivet, and return to the stuck one later.
When the rivet's center pin goes down, use slender fingernails to pick out the
entire rivet, grasping it by its maximum diameter. Again, if this is too difficult,
go to another rivet. As soon as you have picked out one, study it.
When the center pin is put back where it was, you can see that the rivet
grabs both the top and bottom surfaces strongly. If you push the center
pin UP the same amount as you earlier pushed it DOWN, it is not
holding anything, and that is when you insert it (later of course) to hold
the tupperware on after you have done whatever you took it off to do.
TO INSTALL A RIVET
With the center pin a few millimeters proud (means up) from the
rest of the rivet, insert it in the panel and the corresponding hole.
Hold the panel tightly against the frame member, where it belongs.
Push the center pin down so it is flush with the body of the rivet.
Oh, those reluctant ones we abandoned above. Well, you just have to keep
on working with them and finagling them the best way you can. When you
break some, as I have done, take comfort in knowing that they are not very
costly, and your purchase supports a cushy life-style for a sadistic fellow
in Japan, who got rich by inventing them and persuading Mrs. Suzuki to
buy billions of them and use them to put us all at his mercy.
Good luck.
Keith