I just started playing nagauta shamisen about two months ago but I dont really understand notations. I know what the positions are and the simple stuff but I don’t really understand what some of the symbols mean. Does anyone know any videos or websites that can help me out?
Welcome! 
Go to the Bachido “School” link, sign up for a free school account and then enroll in “Crash Course: Volume One” (also free) and go to Chapter 5.16 “How to read notation”
If you speak German or don’t mind Google translate auto subtitles, Su has a notation lesson too: https://www.youtube.com/watch?v=0n1OKuwVsZc