Tap Settings > Aircraft Type Database.
Scroll down to the lower list (shaded light blue). This is a list of types that other AvPlan EFB pilots have kindly shared. Look for your aircraft type in that list. If it's there, tap the row to install it on your device (upper list with no shading). If your type is not there, then:
Tap the + icon in the top-right of the screen.
Tap Basic Details.
Fill in as much detail on this page as you can. Fill it in for the way you operate the aircraft. At a minimum, you'll need to fill in:
Type (e.g. C172 or P2002)
Description (e.g. Cessna 172 or Tecnam P2002)
Fuel Units
Cruise TAS
Climbing IAS (cruise climb)
Climb Fuel Flow
Cruise Fuel Flow
Holding Fuel Flow
Fixed Reserve Fuel Flow
Rate of Climb (cruise climb)
Rate of Descent (cruise descent)
Service Ceiling
Tap the back button ( < symbol, top-left of the window)
Tap Weight and Balance. At a minimum, you'll need to add:
an entry in Fuel Tanks. (Even if you don't know the arm, enter the fuel tank size. This gives you somewhere to add fuel to your flight plan)
Tap the back button ( < symbol, top-left of the window)
Tap Add New Aircraft.. At a minimum, fill in the following:
Callsign (e.g. TOI or 4781)
Registration (e.g. VH-TOI, N4781, ZK-ABC or 24-4781)
VFR Fixed Reserve figure
Tap the back button twice, until you are prompted to save your changes.
Tap Save.
Now you can begin a new flight plan, tap the Aircraft Selection button and select your aircraft's callsign:
The above is the minimum you'll need to have an operational flight planning aircraft profile. Should you wish to submit flight plans, you'll need to add further detail. You can add to an aircraft profile at any time by returning to Settings > Aircraft Type Database > [your type].