Hello there and welcome to the forums!
Medals are won in weekly tournaments. In order to participate in a tournament you must first unlock a tower from the continent map by conquering the province. There is a tower for every age (Bronze, Iron, Early Middle Age, High Middle Age and Late Middle Age). You can participate in any tournament or all at once given the fact that you only use units from that specific age's tower. If you want points in the Bronze Age tower you must use only Bronze Age units and so on.
You can expanding your city with land expansions. These can be acquired in the following ways:
- Rewarded from conquering provinces in the continent map
- Unlocked from Researching technologies
- Exchanging medals for land expansions
- Buying them with premium (as known as diamonds)
Good luck and hope that helps!