Installing New Wheels
You will have originally been provided with an Allen Key / Screwdriver tool that will be needed to carry out the repair.
Other Screwdrivers and Allen Keys of the correct size will also work.
The bolts holding the front wheels into place loosen and tighten in different directions.

The front left wheel bolt (if standing on the scooter) loosens by turning clockwise and tightens by turning anti clockwise.
Replace the wheel and attach this to the scooter.

The bolt that holds this into place loosens by turning anti clockwise and tightens by turning clockwise.

The front right wheel bolt (if standing on the scooter) loosens by turning anti clockwise and tightens by turning clockwise.
Replace the wheel and attach this to the scooter.