I've looked into it in Edmonton, and one option is to visit the offices of the major construction companies, and you can fill out forms to be considered for contract work. Give them a call and see what they say.
If you own your own truck then you wont have a problem finding work as a broker. As it sounds this is new to you, best thing i can recommend is talking with some brokers so you can get a feel of what to charge and how to set it up. Money is great for the most part but if you dont set up agreement that works for fuel then you can get screwed. All costs are the brokers problem but fuel you can set some thing up along the lines that after X amount of mile/liters per day the company helps absorb some of the costs. Brokers can and ususally do get the gravy calls because of this.
But to find work, if you go to a few decent company and tell them you want to be a broker then most will give you a job. Its low risk hire for the company.