Click on the "config" button of the addon on Jira's page "manage add-ons" as system admin or click on "Skills and Profiles" within section "Fields" of issue administration, alternatively.
If you want to add a new profile, you have to determine all related skills, their weight relative to each other (sum of all weights = 100%) as well as their reference value, describing the capabilities of this profile.
So, you can easily set-up a set or library of skills, which are necessary for your environment/company as well as the related profiles clustering sets of skills. Which skills and profiles match your needs cannot be determined in general: you have to find out what you need, but there is a lot of information available on the internet concerning skill lists like https://www.thebalance.com/human-resources-skills-list-2063754 etc. Please also do not forget to talk to your human resource planners.