To use The Common Application:
1. Create an account at https://www.commonapp.org/.
2. Select the institutions you intend to send the Common Application to (you can feel free to edit this later).
3. Fill in all the sections of The Common Application.
4. Complete any “member pages” or “supplemental information” that appear in your Common Application portal based off the institutions you have chosen to apply to.
5. When you are ready to submit, simply click the “Submit” button. Keep in mind that clicking this button will submit the application only to the school you have currently selected. You do not need to send your applications for all schools at once, but bear in mind that you can not go back nor edit any part of your application for a particular school once it has been submitted.
(Source: commonapp.org)