I want to create a plugin how do i do it ?

Hi,

I want to create a very simple plugin but i don’t know how to start, what to do etc. after learning php it seems i have to now learn wordpress api ?

Anyways here what I want to do:

1. Add/modify/delete categroies (not wordpress categories – my own)
2. Add/modify/delete links which are in above categories
3. Then if MSN Bot is there then show these links in appropirate format.

How to create a plugin about this ?

Thanks.