protein skimmer (calgary)

[figdish]

i really dont know alot about what i am building but have been watching many videos on sumps/skimmer/refugiums. My favorite guy is newyorksteelo and he suggests a skimmer with a refugium and it makes sense to me but i only have a limited space so want to make the most of all i have. So I have a skimmer that sits on the back of my tank but don't think it will work for in my sump and need something smaller but enuf room for refugium. I am new to this so not sure what exactly I need.