Unfortunately not really. The best way to learn is to do, but you can watch streams of D3 players, I'd suggest those whose builds you're copying. As to answering your questions, timing and synergy is everything. You and your Crusader should be communicating about when/where they are in their rotation, how much defence/support you can provide for how long, and what the next leg of the rift looks like. As a support barb, you're job is to scout ahead, grouping, and giving defence, in that order. Basically, you start the rift, and you start grouping, remembering that AS-RF is a pull that pulls behind you, meaning you have to get a bit more familiar with maps before you can pull like an expert. Ground Stomp needs to be used away from the mobs you're trying to pull, if you use it in the middle of a pack, they get stunned, but not pulled.
To sort of TL;DR, As the zBarb, you want to stack mobs, provide your defensive buffs, and move on while the Sader kills the pack. Communication is key though, as your Sader can ask you to come back for help, or skip to move past troublesome affixes/mob types.