Basically the list building is you pick a formation, which then gives you the minimum you need to take to include it and then includes a series of supporting options you can take. Once you have that done, you can add other formations (presuming you have the points to buy the minimum units for them) and/or selections from the "Divisional Support" list; while you can effectively take as many formations+formation support as you can scrape the points together for, you can only take one instance of the divisional options. Technically there's an upper limit of 3 or 4 of a given formation allowed, but especially with the West Germans and Leo2s, you'll run out of points long before you run out of formation slots. Also worth noting your "primary" formation is the one that counts for some of the major parts of the game such as morale, which means you want that formation to be the most durable in terms of unit count (which usually translates to it having the most points spent on it).
Going off of
https://tylists.blogspot.com.au/2016/12/leopard.html what your army would be able to field clocks in right at 80 points for a Leopard 2 company (Leo 2s being rather expensive in terms of points at 11 each). You have 2 Marders you can't really squeeze into that list or points limit, but since you were aiming for 80 points anyway that's pretty good.
It'd break down like so (divisional support choices marked with a *):
Leopard 2 Panzer Kompanie
HQ (p.21) - 1x Leopard 2
Leopard 2 Panzer Zug (p.22) - 2x Leopard 2
Marder Panzergrenadier Zug (p.26) - 3x G3 Rifle with Panzerfaust 44 anti-tank rocket, 2x Milan missile, 3x Marder
Leopard 2 Panzer Zug (p.22) - 2x Leopard 2
M109G Panzerartillerie Batterie (p.23) - 3x M109
*Roland Flakpanzer Batterie (p.34) - 2x Roland
*PAH Anti-tank Helicopter Flight (p.33) - 2x PAH
80 Points
You could also try to field it as a Panzergrenadier company, but you'd now be unable to take 2 Leo2s and that would put your list around 60-66 points if you don't mind being a few Marder models short of what you're paying points for.
I am far from an expert on the game, but I have generally seen the Gepard recommended for West German lists as one of the better units in the list. The Roland is fairly limited if the enemy doesn't bring on any air, however the Gepard is able to turn those guns on soft-skinned vehicles (read: BMP spam) quite readily and thus will almost always have "something to do" during a game. Not sure what you might want to shuffle around to fit them in, but likely you'll be able to figure out things that aren't pulling their weight after a few games too. Or, everything is working great and there's no need to include Gepards.
Let me know if I didn't actually make any sense in what I just said; that happens more often than I'd like.