Yes, before you can CC (Crowd Control)( the enemies, you need to wear down their magic or physical armor - the grey or blue bars. Blue for magic, grey for physical. The armor, once gone, means you can, say, freeze, or curse, or catch enemies on fire. The same applies to you, of course ; no more blue or grey bar means you can get CCed, but as long as you have that bar left over after an attack hits you you're immune to those sorts of things.
If one of those source circles is full, then that's what matters. I don't know what character sheet you're talking about, unless you eman the thing what pops up when you hit the "I" key, and even then I've almost never looked at it except to level up.
As long as those little circles by the character portrait are filled in (Notably being COLORED, blue I think) then you have source points. The max you can have at this time is three.
