Unless I'm missing something, given the data fields you've listed, it doesn't look like you can get "average transaction" (there is not Transaction field listed, so nothing to average). As to counting users that completed a transaction, sounds like you first need a field indicating that a transaction was completed (maybe you could use Time of Transaction, assuming that means a transaction was completed). And then you are probably want to count the unique customers that completed a transaction. To do this you'll need to use COUNTD(). To get to this function you'll need to first Extract your data connection. This is because the MS Jet engine doesn't support this function, but the native Tableau data engine does.