Just break off a piece or pieces of your wax melt and place them in a proper unit such as a warmer or a melter. Some of these units are electric and some you use with a tea light.
If using a tea light it is best if the tea light is unscented.
If there is left over wax it will harden as the temperatures cool down.
Some warnings to heed:
Take the wax melts out of the package before use.
Use wax melts only in proper units made for wax melts.
Do not leave units unattended.
Keep out of reach of children and pets.
Do not add water.
Do not melt on stove top or non-approved unit.
Use only in a well ventilated area away from flammable materials.
Do not leave in a windy area (window or fan).