If you want to know more detail about Brokerage I would suggest Value Added by Brad Umansky. He's one of the brokers interviewed in Brokers who Dominate.
Another good read that won't give you a great understanding of the functions of brokerage but more the lifestyle and broker culture, Alpha Male - Sam Foster. (Don't let this scare you though a lot has changed since the time this story took place). It is based off a true-ish story. I actually know some of the people it is based on.
The educational programs are also a wealth of knowledge and they will show your manager that you are serious about becoming a broker. Check out CCIM (101), The Mike Lipsey Company, and Top Dogs. These are great programs that I have personally done. Even if you don't want to shell out the money for CCIM, on their website they have a forum and educational series that you can read.[Here's the link](www.ccim.com/cire-magazine/articles/310927/2013/05/prospecting-101)
There is also the Massimo-Group (started by the author of brokers who dominate) which specializes in helping young brokers. And then you should also check out Bo Barron's website, he's one of the brokers interviewed in Broker's who Dominate as well.
I personally feel the most important thing to read would be the different leases that are used. CRE is built around the lease. Check out Best Commercial Lease Clauses. A lot of brokers think they don't have to know everything because they just use boilerplate AIR leases all the time. You will add a ton of value to your projects and retain more clients if you consistently get your client more than they thought they could get in a lease. It will help your negotiations when the other party says they can only pay X, you go in and figure out how to get that value back through the lease.