1. In compound light microscope there can be seen more than 1 objective lenses. The magnifications of those normally would be 4x, 10x, 40x and 100x. To see the whole structure of the specimen you should focus your microscope with the lowest power objective lens which means 4x.
2. If the specimen you are observing under the microscope is blurry, then you should do fine focusing until you get the clear image of the specimen. The fine focus wheel normally is attached to the arm of the microscope.
3. If your specimen in the microscope is too much bright, then you should reduce the brightness until you can see the specimen clearly. The brightness is caused by the light. To control the light you have to adjust the condenser of the microscope.