How do I calculate the kilowatt hours with the current and voltage readings from my meter?

Oversimplified, multiply the current in amps shown on the meter by the voltage -- likely 120 -- to find watts. Ohm's law says Watts is equal to Volts times Amps in any DC circuit or purely resistive load on an AC circuit. A typical incandescent light bulb is a purely resistive load (contains no motor, electronics etc). A 120-volt light bulb that draws .833 amps is consuming 100 watts. AC circuits are in your home -- not DC. Many connected devices are not purely resistive so your calculated wattage many differ slightly that that actually used.