A standard UK Radiator installation will have hot water flowing through it from an inlet hole, regulated by a Radiator Valve and out through a lock-shield.
The Radiator will have two additional holes, either side, at the top. The most convenient side will have an Air Vent. This can be used to release any air that has found its way into the radiator. The other side is closed off with a Blanking Plug on Column Radiators and a Bush on Cast Iron Rads.
If you want to replace or change these, we have Chrome and Brass finishes for Cast Iron Radiators and Chrome for Column Radiators.