If you want to call Vim to edit more than one file, you can add an option to the command line to open all of the buffers in split windows on startup:
-O
— Open all buffers in vertically split windows, like:vsp
-o
— Open all buffers in horizontally split windows, like:sp
The same can also be done for tabs:
-p
— Open all buffers in tabs, like:tabnew