How to calculate wattage

Help dad.

I am being asked how much wattage I will need in my vendor kiosk. I looked online but I'm not asking for the right thing..

I will be operating a photo booth with a Canon camera, flash, surface pro and a dye sub printer. Maybe some led christmas lights (no more than 300) and a oil type heater.

I will also have a computer monitor and my phone.

How do I calculate my wattage requirements?

Thank you!