A normal pressure network consists of a pressure vat, a pump and a machine using the pressure.
To get started, pump water into the pressure vat. It'll automatically spread to nearby machines.

The higher the pressure, the faster your machines will run.

Whenever your network runs on water, it'll leak water. So you're going to be continously resupplying your network with water.
That's why you're better off filling your network with [link{hydcraft:menu/oil}]Hydraulic Oil[link{}]. This can take a higher pressure and won't leak.