Help with Friends??!!!?

okay so i moved the summer in between 5th and 6th grade. the first day of school i sat at lunch with the most popular table because where i am the most comfortable. and no i am not mean and snobby. but they have been friends since third grade. so all of 6th grade i sat at there table and i ddidn'ttalk much at all because i had nothing to say. i knew they kinda liked me because they said hi in the hallways and stuff. but i never got invited to sleepovers and parties. i really want to. so help me figure out what to talk about and how to get them to hang out with me so i can be apart of there best friends like circle or whatever you want to call it. so how to get them to hang out and what to talk about. and i don'twant to start all over with different people so if ththat'shat you were going to say don't bother!!thank you, and tell me what you talk about at lunch