Basically just need a quick list of the parts I need to complete an upper.
Going with a 16' mid length barrel.
Going to use the A2 style front post gas block
Handguard will be one of those Magpul plastic ones.

My question is what parts no i need in order to finish the upper? What kind of barrel nut? I read something about delta rings?

Any info would be appreciated

the upper of course a delta ring , charging handle, forward assist , dust cover and BCG should complete your upper

Barrel nut (if not coming with the handguard or barrel).

Muzzle device and crush washer (if desired).

 Legion:  Check out the new Magpul MOE SL (slim line) handguards in middy length, very nice.  In addition to the parts you already have, you will need a GI barrel nut/delta ring assembly (best bought together) and a round GI handguard cap to fit between the handguards and the gas block.  Also a mid-length gas tube. A standard GI barrel wrench will serve to tighten the nut/delta ring assembly while a receiver block holds the upper receiver clamped in your bench vise.  I recommend the simple lever tool used to pry back the delta ring so the handguards can be slipped in after the barrel is installed.  It takes some effort but the Magpul instructions are clear enough.  

Be sure to get a gas block/front sight assembly that doesn't require tapered pins to fix it to the barrel.  Clamp on or set screw types are better for the home builder.  You will need a muzzle device and crush washer, or at least a thread protector.  I prefer flash hiders like the GI 3-prong variety.  You will need a ejection port cover and a forward assist.  Personally, I dispense with the latter and simply install a little delrin plug from Brownells, held with a roll pin.  Strike Industries makes the port cover I like.  Buy a name-brand bolt carrier assembly (e.g., DPMS) and a charge handle.  I like Gunfighter model charge handles from Bravo Company.  You will need roll pin punches (available from Brownells) for the pin that fixes the gas tube to the gas block and the pin that fixes the forward assist/delrin plug.

Putting all these parts together seem complicated, but its not.  Much easier than a lower.  Just follow the instructions posted at the top of this sub-forum. good luck - CW