Profile: fields of expertise

How do I edit my working, interests, specialties, general fields on my profile page?

On the bottom left of your profile page there is a link titled "edit expertise" under the title "Expertise". (Also, you can edit your specialties under the "setting tab" under the title "fields of expertise" from your profile page.) Click on "edit expertise", which will allow you to edit your working, interests, specialties, and general fields.