Hey, thanks for playing and taking the time to write us.
You need to assign different behaviours/skins to the mice (you find these in the right corner of the menu, the strong mouse with the bluish shirt or the lover-mouse with the heart. The strong mice collect wood, lover mice.. well lets say they sometimes let your population grow ;)
Normal mice collect food, so be careful of how many mice you change to strong-mice or lovers.
When mice bump into each other they interact and combine items, two times wood makes fire, with fire you can build more houses...
Let me know if this helped you.
Regards.