If it’s a proper water tank it will have a hole at the bottom to fit a hose tail to fit a water pipe (1inch) to supply water to the pump inlet, you will need an inline filter that fits on the inlet of the pump. In the tank you need a ball valve (like fitted in a toilet cistern) to stop the water overfilling the tank, normally the tank won’t have a hole at the top to fit this valve so you need to drill one in.
All the part can be bought on EBay or call Rutland Pump, tell them what you want to do and they will sell you all the bits you need