Though I am not an expert, I would suggest you to read:Originally posted in cdnusers.org by kishore
1. Skill Language Reference Document - sklangref.pdf
2. Skill Language User Guide - sklanguser.pdf
3. Allegro PCB and Package User Guide: Skill Reference - algroskill.pdf
Apart from these a good start is the skill_school forum, where you can find some good lessons by Uri Chaplin for creating forms and triggering them with the help of skills.
Other good resources include:
1. Skill_school forum
2. Shared code - skill on cdnusers.org
3. Source Link
Hope this helps.