A transport ship carrying resources along routes does this automatically. If you want to manually move the fluid, there are two ways to do it.

1. Teleportation. You just need to drag the icon from the ship's tank to the station's tank.
2. Direct docking. Here you need to make sure that the liquid in the ship is above the receiving tanks (artificial gravity works). Fluid flows from top to bottom.

All this information is present in the in-game database (hot key F2). Hope this helps.