This video eplains some reasons for the "note nicknames" Rachel will be using in class:
This next video explains which note nicknames go with each string and finger positions:
This is the finger postition for an open string. No fingers are touching strings. The note depends on the string you play with your bow. So if the teacher asks you to play an "Open D" this is the figer position you want. You just have to make sure you are playing the "D" string with your bow:
This is a "D 1" finger position:
The photo below shows a "D2" position:
The picture below shows a "D3" finger position":