It is very easy to convert a Holdem Manager database. To start, click Tools from the main menu and then click "Setup Assistant". From this window, click Convert Holdem Manager Database.
From the "Covert Holdem Manager Database" window, select the Holdem Manager database that you wish to convert from the list. Below, select the PokerTracker 4 database that you wish to convert the Holdem Manager Database into. (You can convert a HM database into a brand new PokerTracker 4 database by creating a new PT4 database
and then follwing the steps above). It is recommneded you keep the PostgreSQL settings the same, and then click "OK".
Note: PokerTracker 4 will extract the Holdem Manager database and then process it. This can be lenghty for larger databases, but please be patient and let it finish for optimal results.