Defenses and Upgrades

In Starcraft 2 there are three different types upgrades for all of the races. First there are abilities you can research, like the psionic storm for the High Templar; second there are specific unit stat upgrades, like pathogen glands that gives the Infestor 25 more energy; and third, there are general stat upgrades that affect multiple units, like mech weapons an upgrade that gives all mech units increased damage.

 For the defense Zerg have spore crawlers (an anti air cannon that has a detector ability to see cloaked and burrowed units) and the spine crawler and anti ground building. Terran has a missile turret same as the spore crawlers and a bunker that can hold units two marauder, 4 marines, or two reapers in it. Protoss has one building the photon cannon a spore crawlers and a spine crawler combined (all of the defenses needs a building to be able to build them) and that is it on the tutorials I hope this is useful for your game play.