Thank you all. I will wait and see. I will temporarily use phpMyAdmin to backup/restore for now.
I have downloaded PunBB v1.2 to test. I cannot find the Preview button anywhere, Rickard. However, it's fine. It's not essential.

Thank you all for your advice and replies. According to my best knowledge, I cannot find Preview button. Yes, Rickard said that it is included in v1.2. Could you advice where I can download PunBB v1.2? Is it in beta phase at the moment?
About Backup/Restore feature -- it is not part of the bulletin board, but is essential for admin. Since I am not yet an experienced webmaster at present, I hope someone would let me know where to download the plug-in. Thanks!

Dear PunBB authors,
I am new to PubBB, but really appreciate it. The PunBB is fantastic -- it is well packaged enough to include first-class features.
Could I request for the Preview and Backup/Restore Database feature? I think these are essential, and don't make the whole board heavily load. What's more, although we can backup/restore database using phpMyAdmin or something like that, Backup/Restore facilitates more to users, isn't it?
I hope to hear your reply. Thank you!