Here my daughter and I are making pasta dough. Start with 2.5 cups of flour and make a well in the middle. Add 4 large eggs and 1/2 teaspoon of salt in the middle. Slowly whisk in the flour until you get a nice dough. It will take about 15-20 minutes. If you're pinched for time, just through all that into a food processor.
See how thin it gets. I start on the widest setting, run the dough through it, then fold the dough in thirds, and send it through again. What you're trying to do is smooth out the dough before completely thinning it out. Next just run the dough through at each setting until you get it as thin as you need.
You put the flattened pasta on top of the mandolin, sprinkle the top with a little flour, then take a rolling pin and roll it over the dough. The strings of the mandolin will cut the dough and drop it through the bottom.