Re-Save open file under the same filename (Save):
filename (Save As):
The new file name will be prompted in the minibuffer.
Create new file or load existing file (New / Load):
With the mnemonic here for f meaning file. You will be prompted for a file path in the minibuffer.
Visit alternate file
If the file does not exist yet, you will be prompted the path of the file to create in the minibuffer.