Shorten forum description in forumhome

[TRABZONLUKAPLAN]

After you said writing a plugin, I searched information about how to write a plugin.

I opened the page that adding a new plugin. Then I click the place of plugin as forumhome_start because I need to shorten $forum[description] only in forumhome page. Then I gave it a name. And last I wrote a basic statement like below:

$forum[description] = "test";

I made the plugin active but it doesnt affect descriptions in the forumhome. I excepted to write test for all forum description. Whats the problem here ?