There are four lubricant wells in the engine bay

The marks are normally on the side of the coolant reservoir. The cap doesn't have a dipstick. Power steering fluid reservoirs commonly have built-in dipsticks on their caps. If you don't know for sure which fluid goes where, have someone show you. Don't take the chance on getting the wrong fluid mixed in. Some can have catastrophic consequences.

Why are you interested in adding a fluid?