how do i install star trek fleet command

I am still relativity brand new to linux. i have used linux primarily like i would windows but i have come across the problem of how do i install programs. especially i want to install star trek fleet command and im not sure how to do this. most everything i have read so far is gibberish and useless to me as a beginner it seems and the information i have come across most of it is for windows users. i was using windows 10 for a long time and i switched over to linux because i love free and open source software and windows seems to me to be going towards linux style but at the increase price. i have steam but i dont want to pay for a game if it is already free online. can you please help??

peter