Aperture is the size of the opening in your lens when you take a photo. The larger the opening, the more light will get in – the smaller the openinging, the less light will get in. Those different openings are called f-stops.
small f-stop = large opening
large f-stop = small opening
Therefore, when you set your aperature, keep in mind the lighting. If it’s darker where your working, use a larger opening (smaller f-stop). If it’s brighter where your working, use a small opening (large f-stop).
Make sense? Have questions?