Execute WordPress Plugin From Token?

Ok, bear with me as I spend most of my days writing C#, JavaScript, HTML, etc. and not PHP.

I am trying to create a WordPress plugin. I would like someone with edit rights to be able to place a token such as [[DONATIONFORM]] in the body of the page content. At runtime that token would be replaced with an actual form.

I have gotten as far as defining a plugin and having it show up in the list of plugins. I have created a function in one of the plugin files called GenerateDonationForm(). I just don't know how to have it run when someone puts in a token.

via Chebli Mohamed