|New Enemy Units||
Before the campaign actually gets under way the game provides an optional tutorial at the beginning of the Terran campaign. The requirements of the tutorial are quite simple and designed to simply get you familiar with the basics of unit movement, resource gathering, and construction. The objectives are to construct 3 Supply Depots and a Refinery, and collect 100 Vespene Gas.
When the game starts you will notice that you only have one SCV and sixteen marines. Your Command Center is also quite far from the main mineral patches so lift it off and place it closer. You also don't have much open supply in the beginning (it would be somewhat useful to kill at least four of your own marines in order to free up supply to create more SCVs). Get to work immediately gathering the provided minerals with the SCVs and begin construction of a few more. Continue putting the SCVs to work mining as they appear. At least 4 to 6 SCVs should do for this mission. Before advancing onto the next level, definitely practice coordinating efforts as efficiently as possible; you will learn much about economy management by doing so.
It is very difficult to lose the tutorial and you will never have to face an enemy attack. As your SCVs work, you should familiarize yourself with how to attack with Marines, your attacking units. You should practice rotating marines to avoid losing any HP; you should be able to consistently defeat all of the Zerglings without getting a single Marine injured.
As you get past 100 minerals pull one of the SCVs off of mining in the mineral field and send it over to begin building a supply depot. You can build it anywhere around your base although to avoid clutter it is recommended you try to build it away from your SCVs working. In order to construct a supply depot select your SCV and click on the basic build button at the bottom of the command selection screen in the bottom right corner. The Supply depot will then appear in gold in that same window for you to select and place. You will need 3 Supply Depots in order to complete the mission.
After you have the Supply Depots, wait for another 100 minerals and construct a Refinery. You can construct a Refinery on the nearby Vespene Geyser which allows you to mine for Vespene Gas. Like mineral patches, Vespene Geysers can deplete after some time of mining but Vespene can still be mined even after it's "depletion" though the amount you get from each trip is reduced from 8 to 2. Some of the more advanced units and buildings in the game require Vespene Gas in order for them to be made. Once the Refinery is completed, switch at least 2 or 3 SCVs from the mineral patches to the Refinery. Normally, 3 or 4 workers on one Geyser is ideal for maximum Vespene gas production efficiency. All you have to do now is to wait for 100 Vespene Gas to be gathered.
Once all mission objectives are complete, you will get a message from the Terran advisor that you have completed the training, thus completing the mission.