Need help on QoS over WAN link

[180990]

I have Nortel ERS-5520 at remote site with voice and data VLAN's. 5520 is used as Layer 3 switch connected to provider's WAN router through routable VLAN link.
I was told that I need to tag WAN packets with Diffserv (DSCP) and shape the traffic on the ingreess.
I was looking at some QoS commands and I'm so confused to the point where nothing makes any sense. Trying to put things together makes me even more frustrated about this QoS stuff.
I was wondering maybe somebody out there would provide me with some examples to get me out of this QoS nighmare and make this setup work.

Cheers!

 

[VinceWhirlwind]

I can't recall exactly what I did, but I still have an old config and it has this in it:

qos if-group name trusted class trusted
qos if-assign port 1-24 name trusted

and then a bunch of stuff that looks like default QoS config.