The enlarger machine has many different parts. Near the top of the machine, there is a light bulb, a focus lever, a zoom lever, and a negative carrier where you put your film strip. Near the bottom, there is a blank platform where you put the film paper.
First you put your negative film strip in the negative film carrier. You put it upside down so it will be projected the correct way. You then turn on the light to see it projected onto the blank platform at the bottom of the machine. Once your picture is projected, you can use the levers on the right side of the machine to zoom into your picture and make it larger. You then make a test strip. A test strip is a strip of photo sensitive paper that you use to test how many seconds are needed to expose the projected image onto the photo paper. You turn the timer to two seconds and expose your picture to the test strip by pressing on the timer button. The image is projected onto the test strip. Once you have chemically processed the test strip, you'll be able to see what the photo looks like. You can tell which time is good for your photo by looking at the light and dark areas of the test strip. Light areas are classified by the number two. You count by two to classify the shades up from the darkest. You expose your actual picture for the amount of seconds whichever shade you liked most on the test strip is.