Following are some resources and links to learn about Sakya Lineage of Tibetan Buddhism: 

• Basic information about Sakya Lineage: http://hhsakyatrizin.net
• Introduction to Sakya Lineage Founders: http://hhsakyatrizin.net/the-sakya-tradition
• Sakya Monlam held in North America: http://sakyamonlamnorthamerica.org/