Leveling Up an Arcane Familiar

[andreana22]

I created a wizard and gave it an arcane familiar. The character is now at level 3 but the familiar is still at level 1. How do I level them up to 3 to match the wizard? There is no Journal tab on the familiar's view. There is a place to "Click here to add class levels or hit dice" but the options are classes like Cleric, Fighter and Monk.I didn't think that familiars had classes.