add_filter??

[eru321]

Thanks for the answer. I'll try to be more clear.
For example, the mp3 plugin.
I write (% mysong.mp3 %) in the page where i want to insert the player.

I would do the same thing with my plugin.

Use add_filter to specify a function in your plugin as content filter.
In this function use a regular expression to find the (% ... %), which belongs to your plugin and replace it with the desired text.

THANKSSSSSSSSS A LOT!
It Works.
Really really thanks.