Rather than do something here already done, I'll let Pippa explain the basic controls and how to start using either a stereo or monocular microscope. The compound monocular she is using is still a basic microscope although it has a moveable stage, an iris aperture and a substage
condenser... remember: the last two focus and manipulate the light beam so it shines up in an optimum way through a specimen and up through the optical path (the objective
and eyepiece lenses). Your budget starter microscope will probably not have these means to optimise the light beam. We'll go into more detail about the importance of controlling the light in a moment. But for now, you can understand that the sub-stage aperture is a hole (or opening) which can be varied to get bigger or smaller, and the sub-stage condenser turns the light beam into a tight, bright cone of light. The point of the cone hits the specimen on the glass slide and passes through it in a tight light
A common error for first time users: the key thing to watch out for is looking at the gap under the bottom lens when the turret is turned to select another objective lens, and when winding the coarse focus up. Always look at what you are doing so as not to ram the lens with the glass slide. Pippa will show you in her video.
Pippa made a small suite of movies to help young people get started in Microscopy as an educational hobby. The videos are located here.
She also has a book you can buy to help youngsters get started. It's available here.
Sadly, Pippa has been through a series of difficult illnesses in the last 2 years and her help here to others was brought to a close.