you should be able to push them straight onto the motherboard, this is the quickest way
get the power switch cable ussaly 2 pin or 3 pin, from the pwoer button on the case, plug it in to where youre motherboard maual says it should, and plug the pc in at the mains, connect it to a monitor and hit the press the power switch, hopefully it will turn on.
front pannel connections cant really damage the board or get damaged to easily, so just work you're way from there