To add a co-author, open the record of a publication and go to section 'Authors and affiliations'. Click on the button 'Add person'. You can search for authors that are in Pure already or create a new external person. Notice that if you click Edit opposite the person’s name, you can select the role of the contributor (for example if you are an editor rather than an author). Change the order of authors by clicking the up and down arrows, and remove a person by clicking on the minus sign.
Please note that if you are adding a chapter in a book or other edited work, you should only add the authors of the chapter in this section. The Editor(s) of the host publication should be added by clicking on the button 'Add editor' in the Publisher section.
Please consult Pure support pages on adding publications to Pure.