Oh StarCraft, you make me feel so damn old. I remember playing you to the early hours of the morning. Both on PC and the Nintendo 64. Hell me and a friend figured out it was possible on the N64 to build 36 nukes as the Terran then pretty much fill the screen with their explosions. It was a good time for all. I mean not the place you dropped them, that was dead. The game itself is a real-time strategy game where you build troops as one of 3 very distinct races, the humans known as Terran, the insect like Zerg or the technologically superior Protoss. They all have their own strengths and weaknesses so pick your poison and practice away, I always liked the Protoss personally.
The game is amazing and to this day has a heavy online community even in multiplayer, tho most people have moved on to Starcraft 2 or the Remaster of the original. You can play the original for free however, and there is no reason not to at least try it out. the game still is a lot of fun if not graphically inferior to look at, I mean it is about 20 years old. It is still fun to play and not bad to look at compared to many games from its time, and its easy to see why all these years later it is still big online. Best wishes and may the gaming gods bring you glory.