new person... affinity question

[world of sports]

Hello, I am a new person with magic. I am converting from YU-GI-OH...

I have bought a box of steel and mirodin and a few older packs to try to get a variaty.

I have a dumb question on affinity... when you have artifacts out and the card says pay one less for each atrifact along with having 2 blue mana...
now do i still have to turn the blue mana even if I have artifact mana that is blue....

Now what happens here.
I play mycosythn lattice:
I play a artifact from my hand with that says 2(2white).... with affinity...now since everything is change from my hand will I have to still turn the 2 white...
Thanks for all the help

[Crimson Golem]

Affinity only takes away colorless mana cost. So if it's 8UU and you have 10 artifacts in play you would still have to pay UU for the 10/10 Broodstar.