To create a skills hierarchy, add the Parent category field to your skills, certification and category page layouts.
[Optional] To use a skills hierarchy, add the Hierarchy Level and Hierarchy path fields. These fields define where the skill sits, and its level, in the hierarchy.
Click Setup | Manage Users | Profiles and select a profile. For each profile you want to use a skills hierarchy, on the Profile detail page, in the Page Layouts section | Custom Object Layouts, under Skill/Certification, click View Assignment. Assign the Category layout to the Category record type for any relevant profiles.
Click Setup | Manage Users | Profiles and select a profile. On the Profile Detail page, navigate to the Record Type Settings section and in Skills/Certifications, click Edit. Add the Category, Skill and Certification record types to all user profiles who use the Skills and Certifications page. Click Save.
[Optional] Edit the Type, Group and Certification Source picklists on the Skill/Certification object to align them with your organization, or remove them from your page layouts if not required.
Add the Skill and Certification Ratings related list to the Contact page.