Congratulations!
You could certainly use them for a skirmish game. I would be very surprised if you couldn't find some rules for that, though I don't know any myself.
If you want to play a mass battle game with a small number of figures, the best choice is
De Bellis Antiquitatis. Every army has 12 units (bases) and your figures you have now would count for nearly five of them. Heavy infantry have four figures per base.
The DBA book contains the army lists. I don't know what Troop types are in the Etruscan list. It probably has some lighter troops for which you use fewer figures per base.
Here is a great website about DBA.
http://fanaticus.org/DBA/index.html