Dash cameras come in two forms - With accessory plug, which simply plus into the vehicles accessory socket (known as Cig lighter socket). or as three wire connection. The three wires are :- Ground - to be connected to chassis Bolt, Ignition - to be connected to ignition live wire and permanent 12-36v. If you are unfamiliar with a vehicles electrical system do not atempt to install but seek professional help.
The Piggy Back fuse holder will allow you to install the cameras wiring loom. simply identify which fuses are live and ignition at the vehicles fuse box. remove the fuse and insert the Piggy back holder, then reinsert the removed fuse into the Piggy Back holder.