How do I make wave system?

Hello, I want to make wave based game and I need help to make this type of system. So I have a timer it goes from 2min to 0, then from 1min to 0, then from 2 to 0, then 1 to 0 and so on in an infnite loop. The enemies should be spawning during those 2 min randomly across the map. Also I need somehow to manage the number of enemies. each round enemies have a little bit more health, do a little bit more damage or spawn more enemies. After some rounds I want add some different enemies. That would be it. I’m beginner at UE so any more detailed description would help a lot. Thanks.