Open up a Token's settings by double-clicking the Token, or by left-clicking it and selecting the Cogwheel from the context menu. From there, there will be a tab called Dynamic Lighting. Go ahead and click it to view the various lighting and vision settings. Each individual Token will need certain settings enabled to enact the light or vision scenario you are intending. For example, a Player Character Token will need some sort of change to their Token Vision settings, while a torch Token will need some Token Emits Light options enabled. Read about those options below so you can set up your Token appropriately.
Make sure that you also set a Token's "Controlled By" field (under the "Basic" tab) if you want your players to be able to move the Token and see what it sees.
If you want this Token to be able to see, turn on Vision. When a token has Vision, it can only see up to the edge of what is illuminated by light sources.
Token Emits Light
If you want the Token to emit a Bright Light up to a certain specified amount in feet, then enable this option. Bright Light on its own has a feathered "edge" starting at 1/2 of a grid cell before the edge of the Bright Light.
This option changes the effective radius of light as viewed by the Token. A setting of 200% will let the Token see light from twice it's set radius.
Is There a Guide to Common Settings? Do you have Lighting Setup Recommendations?
Absolutely! There is a guide to some common settings and lighting/vision setups available here.