how to mine minerals and get gas

Mining minerals and harvesting gas is the most important activity in starcraft; without minerals you can't do anything!  all buildings and units require minerals, for example the simple  SCV take 50 minerals, the medic takes 75 minerals and 50 gas, and the command center takes a whopping 400 minerals. First you box your SCVs (left click and drag over them) then you set them to work on mining. Next you build more SCVs and you check on your supply if you are close to the number next to it build a supply depot. Finally build a barracks and some marines. Once you feel like you have a big enough army move out (I only attack when I have 200/200 supply)