There are three tabs on the top left when you're inside a guideline, References, Evidence profiles and Recommendations.
When you are in Reference view you can edit and add References
(add abstract, PubMed ID, add results and comments)
When you are in Evidence profile view you can add and edit the PICOs /Evidence profiles.
(add outcomes, do quality assessment, write summary, add references, add codes and get suggestions for new evidence)
When you are in Recommendation view you can add and edit the recommendations
(add PICOs, write key information, Rationale, practical advice and more)
Every section has a menu on the far right of the banner. In that menu you find options to add References, PICOs and Recommendations to the section.