well i really want to download the plugins here but i don't know how to have mybux?
what should i do to get this??

To download any of the exclusive modifications that we have here at MyBBSource, you must accumulate MyBux. MyBux is MyBBSource's virtual currency. By posting in these forums, you accumulate MyBux which you can then use to purchase modifications or use them to exchange services in the marketplace. The more constructive your post is, the more MyBux you will earn.

By going into the Modifications tabs, and searching through the mods you'll see how much MyBux each one costs. Once you purchase a mod, you will then have access to it forever.

For more information, please view the MyBBSource FAQ entry.

I believe you get 2 MyBux for each good post you make?

Correct, it shows exactly how many MyBux you can get here: http://mybbsource.com/misc.php?action=help&hid=9