Hey, I want to do an IRC Bot which bans/to people which post something. Like h*tler or http://puu.sh/jU5PH/c3de3a4d48.png. But I dunno how to do it and where I have to put the file for it. Thanks for helping me.

//push

The event you're looking for is on text.
/help on text
The function you want is ban and kick. Considering that you're using it for twitch you'll have to know how to ban on twitch since it's not the same as mIRC unless you're patiently awaiting Froggie's mTwitch Normalizer.

Then you need to figure out how to catch certain words in a string, best used is Regex which can be read about over here: http://www.regular-expressions.info/ you can use regex in mIRC as an identifier: $regex() or in the actual on text event.

Yet again I have done this in the past but forgot the script. You could make it where you set it so only people with a value less than 100 can join so you can make it for when your bot kicks them it automatically sets there value to something like 101 so they can't join