Ground services like catering, luggage etc have to be ordered through ground services using the radio. This can be accessed with the “Scroll Lock Key” and also by placing your mouse on the little triangle in the center of the screen and selecting the “Tower” symbol. That will pull up ATC. Then you can call ground and then select services.
The fuel is on the same menu , select the little symbol that looks like a “Weight”
Many people didn’t realize it was there under ground services when you are near a gate or parking.
just turn to ground.
Remember to turn off engines, and APu generators (overhead panel), switch to external power (overhead panel)
(power truck may be needed depending on your settings).
Then connect jetway, do luggage and catering. IF you have ot park in a different spot because of another player, you have to click each twice, first will say not available but spawn the truck, click again to get service on each.