Tallying

I'm looking to perform the following operation. I know that we don't actually have the primary/foreign key setup completed yet, but I'm using the terminology to refer to

Form 1 records information with the primary key being the 'user'; the data contents of the form are many and of a fairly varied nature

Form 2 records information with the primary key being an 'action'; the foreign key is the 'user' Form 1 is keyed to (it's keyed to other things, too, but I'm not concerned about that just yet).

I want to record information about the 'action' described by Form 2 with respect to the user in Form 1. I don't need to record much, is my current thinking - just the numerical fact that a new entry has gone into Form 2.

In my old setup for this, I had a checkbox field in Form 1 that was intended to reflect a basic true/false on whether or not the user had performed the type of action contained in Form 2. However, I think I actually need to tally the number of times that a given user has participated in such an action. Is there a way, then, to have Form 2 pull the current entry in the Form 1 field that describes the number, add 1 to it, then send it back to Form 1?