Hi there! I'd like to get some help on throttling traffic to a specific website.
Please go easy on me; I am only used to residential and "SOHO" routers. 
I did some looking around in the GUI on the router, but quickly realized it is far more complicated than the Linksys and Netgear routers I've used in the past. I'm sure it's easy to do if you have experience, but this is our first 'enterprise' grade router.
Also, I called some local IT companies in our area, and none of them said they had experience with this series, so hiring someone to do it is a no-go. I only found one company that works on AdTran equipment, but they work for very large companies, with 500+ employees at a single location, so they didn't even want to touch our case (and we couldn't afford their rates, anyways!)
Basically: We need to throttle the UPSTREAM connection from any user on our network to a specific website. This is a file sharing website that we use all the time, every day, and there is no way to throttle the traffic except the router. When a user uploads/shares files, there is no upper limit, so it 'saturates' our upstream connection and everyone else's internet gets slow, and our VoIP devices often drop out. 
I've looked through QoS maps and some of that, but I am worried I'll make a change that gunks up the entire works. Without an expert in-house, and no expert in our town, it's up to me (scary thought!) and an easy-to-follow set of instructions would be super duper helpful.
I would appreciate any and all help, recommendations and instructions on how to do this. I'm used to SOHO routers, where I can simply enter an IP or domain, and very easily set up throttling using QoS. I admit I'm a bit over my head here, so no comments about "woulda, coulda, shoulda!" 
Thank you!