hello can somone help me in halo 3 in capagain i need to finish the ark,cortana,halo,and the snow level i think its called the covenant

ON LEGENDARY iv allready finished in easy but i need to finsih some levels on legendry

i need the body parts and the achivment

and if u have time can u help me with some skulls i need the hyabusa helmet lol and the achievment

SO CAN U HELP ME????????/ MY GAMERTAG IS xb3333

than you