How to start a conversation with her and talk to her?

One day me and my friend walked in our high school caffeteria and saw this really cute/ beutiful girl who we both now like, shes smart, and has a beutiful smile, i really want to talk to her but i get nervous when she walks past i even tried sitting at her table. i notice that when im looking at her, she is looking at me and im not sure if thats a good sign. also im really good friends with her best friend so maybe she could help. but wait theres another problem, my friend who likes her, hes told everybody including her friends and there trying to help him with her, even though she pays him kno attention. this is the first time i have been scared to talk to a girl plus shes always with her friends so its awkward... btw we have know cles together, i only see her in 35 minute period before homeroom and at lunch please help.........