To edit your resume, login into your account and visit your dashboard using either of the two options.
You can use the arrows next to the title of your resume to scroll between the current resumes on your account. There is also an option here to change the template for your resume.
Then, click on the section you want to edit. This will take you into the editor, where you can edit all of the content in that section. Click on the section you want to edit or add to.