There's no need to select random teams, you can manually type in the names of the teams. Just be sure, simply for your own sense of wanting it to be neat, to spell them the same way you'd originally saved them.

Also, when conducting a finals match, you'll probably want to keep the score. Non-fixtured matches don't automatically save the score but you can force it to by choosing the relevant option under 'scores'.
Footypedia, a labyrinth of local aussie rules history - www.footypedia.com