How can I connect mains to a 230V heating band?
The data is insufficient. Apparently the link you have added is region specific. Most heating pads work in AC. Using that basis, the + and - you have mentioned are Live and Neutral. However if you intend to earth your connections, just short the neutral wire and the ground wire. Your heater works on general wall sockets.
Since the power specified is 235 watts, The Voltage will be 230VAC and Current 1A which works fine in a normal socket