Experience is gained after each game. For conquest, experience is calculated like this:
Earned Cp / 2 + 1000 xp if you win / 500 xp if you lose.
Experience may also be gained by selling items. Yellow items sell for 200XP, Green items for 400XP, etc. Veteran's medals sell for 200XP, Hero's sell for 600XP, and Legendary sell for 1000XP.
Mark II is 15,000 XP, Mark III is 30,000 XP, Mark IV is 60,000 XP and Mark V is 120,000 XP.