Benji77 Okay, you need to take step back and slowly think this through.
Dont worry about your composition for now.
Your immediate priority is to understand exposure.
Exposure is the calculation of light/dark that you have to control via
your APERTURE, ISO & SHUTTER SPEED.
Used together, each change in each component affect each other.
HOW they affect each other is what you need to know.
WHEN you want to use each of them (exploit) is your key.
WHY you choose the component is up to YOU.
This is the advantage of MANUAL mode.
It allows you to do what YOU want.
put your cam on a tripod or table.
focus on anything.
Set to manual, adjust any of the 3 components till you get a 0 (zero)
rating in your exposure reading.
Check what you get. it should be correctly exposed.
now using what YOU want to achieve in the shot, use the WHEN & HOW to get what you want