As Space Marines, you choose your Chapter, then Commander before you join a game. Commander choices are horse Commander (offensive) Apothacary (Healing) Techmarine (Defensive)
Coulour Scheme's arn't correct
When you start the game as a horse Commander, you start with a HQ (This is the only building you have) a Heavy Bolter turret, your horse Commander and a scout squad.
The resources are Power (Increased by capturing Power Nodes, which you can upgrade to have Plasma Generators on the Point aswell) Requistion (Increased by capturing Requisition Points)
Your first selection option for unit building is a Tactical Squad, Heavy Bolter Devastator Squad and Assault Squad.
More things which are very incorrect about Space Wolves (Which is what I've been playing as)
When you upgrade your base to level 2, you gain Plasma Cannon Devastator Squads, Dreadnaught's and Razorback's (Which can transport 1 Squad)
Level 3 gives you access to Predator's.
All Squad's a 3 men, which is very much against the Codex Astartes :/ as Squads should be 5 or 10men generall.
Scout Tactical and Assault Squads can be upgraded to have a sgt, so making them 4man Squad.
With your power bar (Increased by killing things), you can use it for Orbital Bombardment, a Tactical Marine Drop Pod, Deepstrike of Terminators or Assault Terminators and a Power Up of damage for a squad. - These Powers vary between type of commander your playing.