If you are coming from Mexio you will need to buy a step down transformer (voltage here is 220 and North America is 110). They are readily available in the souqs as well as Carrefour hypermarket. The pins for your appliance/laptop will fit into the transformer itself, the transformer is then plugged into the wall outlet.

One thing to be careful of is the wattage of the appliance you are connecting to the transformer - hairdryers for example generally have a high wattage so you have to choose a transformer that can handle it - it will be clearly marked. I know your computer will be OK - and probably doesn't need the transformer (check your computer documentation) just an adaptor for the outlete.