this was postet by flip in the discussions, i posted i here so people find the info they need. thank him, not me :)

For Conquest
You research units to unlock. You purchase units from the left box, they then go into your reserves. You then move units to your reinforcement slops on the right, you start with two unlocked, I & II but can research more. Slot 1 has 50 points, so you can assign 50 points (represented by a helmet) of units in that slow, Slot 2 has 60 points etc. When a match starts (press Campaign, select a map and then start) you can call these in as you earn points, they will show up on right of screen and light up when you have enough points to call them into battle.

For the research tree, starting from the top you can begin research to unlock different things.

Top Row -> More reinforcement Slots. You start with 2 slots, I & II, each slot you can assign units to call into battle. You can research more slots so you can call in more reinforcements.

2nd Row -> Defences: Research defenses

3rd - 5th Row -> Special Infantry (note: 4th Row lets you research Airstrikes). Typically small teams like 2 man AT teams, medics, flamethrowers etc.

6th -7th Row: Infantry

8th Row - Armored infantry Transport like halftracks.

9th - 11th Row - Trucks, ranging from empty transport trucks to ammo supply trucks etc.

12th Row - Self propelled arty I think

13th - 18th - Infantry support weapons including machine guns, Anti Tank guns, field support guns, 20cm Auto-cannons, mortars etc.

Pak = Anti-tank guns
IGs = Anti Infantry Guns (good stuff)
FH = Field Artillery
Neubel = Rockets

19th - Light Vehicles

20th - end - Various tanks. You will need to do your own research to find out what each vehicle does (wikpedia will do) but a short rundown

Pz 35 - 38 + Marder = Captured Czech and polish tanks I believe.
Pz 1: Panzer 1 light tank, armed with machine guns
Pz II: Panzer II Light Tank, armed with machine guns and 20mm Autocannon
Pz III: Panzer III Medium tank. Early version will be armed with a small calliber anti-tank gun, I expect later versions (see Letter next to name) will start to equipped anti-infantry guns. Long barrel = anti-tank, short barrel = anti-infantry
Pz IV: Panzer 4 Medium tank - Opposite of Panzer III, early version armed with anti-infantry gun, later versions equiped with long barrel designed to fight tanks.
Pz V: Panzer V aka Panther Tank - Heavy Tank
Pz VI: Panzer VI aka Tiger Tank - Heavy/Medium tank (depends on who you ask)
StuG: Self propelled gun, short barrel = Anti-infantry, long barrel = anti-tank. No turret