If you haven't read
Making a definition covering open raising and
Making a definition for three bets yet then please read them first as this tutorial assumes you have read them.
A four bet is similar to a three bet but another raise has to take place afterwards. In this definition, our OpenRaise is going to be marked as having been made by the note recipient.
This isn't required. It doesn't matter who open raised as long as the note recipient four bet but this is an example to show flexibility and so we select this as an open raise/four bet combo. The FourBet action is actually identical to the "OpenRaise" action which should make sense.
In between sits the ThreeBet which should be perfectly logical to you by now
Here is the completed definition (right click->save as):
RaiseThen4Bet.xml