When you want to buy credits, ask somebody with enough credits and tell them what you want (ex. archon brigade armor = 2000 credits) So they buy...
1) the newbie city (poeta or ishalgen or w/e) 2,3,4) in sanctum/pandaemonium 5) tigraki island (its a hidden island in the abyss; google it) 6,7)...
You use the "extraction tool", which can be bought from the general goods seller on the item you wish to extract. In doing so, you will get...