What wonderful parent your Uro has! Keep asking questions! 
I have found that the amounts depend a lot on the time of year, and the Uro itself. As well as the food you are offering, since they each have their favorites.
Feedings uros can be very complicated, or fairly simple, so its ok if you start off with good staples and then add things along the way. One thing that will make a big difference is whether your Uro is wild caught (WC) or captive bred (CB). If it is captive bred, and already eating greens well, then you are well on your way! If it is WC then there may be some additional steps you have to take.
Ok, amounts.
If you have a juvenile I would start with 1/2 to 3/4 of a cup of chopped up greens. I was told once that a good rule of thumb is "nothing bigger than the space between their eyes". I didn't know exactly how to measure that then, and I still don't, but it will at least give you an idea!
There is a school of thought that feeds whole leaves... but I always cut mine up. For your specific uro you could feed a half cup in the morning, and give him more if he has eaten a lot of it by the evening, or start with a bunch and sort of cut back until he seems to eat most of it. Mosca is a small egyptian, and it constantly astounds me how much he can pack into his belly! (He will often polish off a 10in plate full of his favorite greens now!)
I feed once a day, and leave the uneaten greens in the cage until I feed again. My observation is that they will oftentimes munch on the dried greens as a snack, but some schools of thought have you remove uneaten greens after a certain amount of time. For my schedule, since I am most decidedly NOT a morning person, and to help Mosca's "bonding" with me, I feed in the afternoon, right after I get home from work. The way his lights are set up he still has 5 hours of light after that time, so it works out fine (seemingly). I think the main thing to remember is that they can't digest food as efficiently when they are cold, so you want to feed them when they will still be "day-time" warm and toasty for at least a few hours afterward.
Since I only have the one lizard, it can get irritating (and smelly) to buy a bunch of different greens every week that are going to go bad long before I can feed them, so I rotate each time I buy greens. Though relating lizard and people husbandry is generally a bad idea, I do the same thing for my own diet. As long as they are getting a variety over time! I have difficulties finding a lot of the greens (particularly dandelion greens) around where I am, the grocery stores do carry some of them, and oftentimes what Mosca gets that week is dependant on what looks the best at the store. If it doesn't look good enough I would eat it, I don't consider it good enough for him.
I personally supplement his food with calcium and a multivitamin, if you got your uro from a breeder they can tell you how many times ea. I usually do 3 times a week with the multi and twice for the calcium.
Anything on top of the greens like summer squash, organic edible flowers (YUM!), the occasional pea, or the very occasional thin apple slice (as a treat, my last uro would do just about anything for a sliver of granny apple) is gravy! As you get more sophisticated with your Uros diet there are all sorts of things you can add and play with. Bee pollen used to be used mainly as an appetite stimulant, though I have noticed people feeding it more and more as a staple.
I also fed pretty bird finch food as an occasional supplement when Mosca was a juvenile (the completely not natural looking, bright colored kind, smells like fruit loops). As an adult, juvenile iguana pellets are more suited. Though Mosca isn't a big fan, so he occasionally gets some of the bird seed, since he seems to really like it.
So, I have probably added to your confusion, lol. Summary: Get the basics down, feeding lots of yummy greens, and a good supplement regimen (imo - I use herptevite brand personally). Then you can start adding new things in! If your Uro isn't eating well, then there are other things to try.
I hope that helped a *little*. I at least gave you some tentative amounts! 
Elizabeth
-----
1.0 Mali Uro Archimedes (May he rest in peace)
0.0.1 Egyptian Uro Zuberi Mosca Khu (Mosca)
0.1 Sulcata Minnie
1.1 Iguanas Flik and Loki
Madison, Wisconsin