Noob fuel question

[Pionpion]

Hi all
Haven't played the game for years and I'm currently having troubles getting fuel supply to my forward panzers.
I wonder how I should organize my supply chain.
Do Corps HQ draw form Army higher HQ they are attached to to a rail TErminus ?
Do I have to occupy the railhead with my Army HQ and place my Corps in range of this HQ ?
Or do I have to advance my Army HQ as fas as possible to supply my Corps HQ up to the units ?
All my units are within range of Corps HQ, but they are in red for two turns now.
Thanks for your tips.

[AlexSF]

Corps HQs draw supply from railhead only, not from their Army HQ. You want them as close as possible from the nearest supply point/railhead.