Well, after you've received a list with certain orders to find and purchase, you have to go on a supply run. If there are no Depot Masters and no Provision Officers, then the assignment will be led by the Master Chief of Engineering or another high ranking member of the other sub-professions within the Engineering Wing. Also, in case the Suppliers lack members, then Mechanics and/or Technicians will have to assist. Anyway, here is the format that you must use when you write a supply run report:
Planets visited during the assignment:
Mission starting time & date:
Mission ending time & date:
Purchased equipment:
Price paid:
Mission leader:
Mission participants:
Mission status:
Mission report:
Please make the mission report a bit more detailed in case something important happened during it. If everything went well and if you've managed to purchase all the ordered equipment, then make the report as brief as possible. And yes, you do have to count how many credits did you pay for all the supplies. There's always a starting price, but failed or successful negotiations might either lower or raise it. More equipment information will be uploaded into the Mechanics' database, so don't worry...you'll know how much each item costs pretty soon. Oh, and all the reports must be written in a different topic in the Suppliers' section.