Hello Susieo! Congratulations!
The button style locks are a pain to close but with a little practice you'll find that you can pinch it closed with both hands, then hold it in place with one while you slip the button over using the padlock hasp. It's like anything else, once you do it a few times you'll become a pro!
The button is necessary because it keeps the layers of metal tight enough so the post remains straight:

- chinese-lock-a.jpg (11.38 KiB) Viewed 9080 times
Without it, the tension on the waist belt will cause the post to lean, deforming the part of the belt it attaches to. Eventually, that attachment point will tear leaving you with a detached post and an oblong hole where it used to be. This happened to my Chinese belt because I also skipped the button.

- chinese-lock-b.jpg (11.5 KiB) Viewed 9080 times
When my post tore off my husband solved the problem by drilling the holes relating to the post to 3/8". He bought a 3/8" stainless machine screw and nut at home depot and modified them. He ground the head so it's flat against my skin and drilled through the shaft of the screw for the padlock hasp to slip through. Locking me up was easy - I'd push the screw through the back, slip the other two layers on top, and spin the nut down the screw so it's hand-tight. This held the belt together and was much stronger. The padlock was slipped through the hole in the shaft of the bolt to make sure I couldn't take the nut off but it was the nut that held it together not the padlock.

- chinese-lock-c.jpg (10.34 KiB) Viewed 9080 times
Another option is to replace the post and button with a computer lock as Pyra Gorgon wrote about on
this thread!
Molly