The 70-200 mm is the "third" lens wedding photogarphers use when they are shooting the candid shots during the reception.
With as little you know about photography in general and wedding photography specifically, you really need to work as an assistant to a working professional photographer before you take on such an assignment. Remember, there are no re-shoots for weddings, sports or breaking news. One of the reasons only seasoned photographers usually take on those kinds of assignments.
No matter what you may have "heard" or "read" the most used lens by wedding and other event photographers is the 24-70 mm f/2.8 and 50 mm f/1.4 or f/1.8 when using a camera like yours. If they are using a full frame camera, a 85 mm or 100/105 mm portrait lens is used instead of the 50 mm.
With as little you know about photography in general and wedding photography specifically, you really need to work as an assistant to a working professional photographer before you take on such an assignment. Remember, there are no re-shoots for weddings, sports or breaking news. One of the reasons only seasoned photographers usually take on those kinds of assignments.
No matter what you may have "heard" or "read" the most used lens by wedding and other event photographers is the 24-70 mm f/2.8 and 50 mm f/1.4 or f/1.8 when using a camera like yours. If they are using a full frame camera, a 85 mm or 100/105 mm portrait lens is used instead of the 50 mm.