How can I edit multiple files in VIM?

First of all, in vim you can enter : (colon) and then help help, ala :help for a list of self help topics, including a short tutorial. Within the list of topics move your cursor over the topic of interest and then press ctrl] and that topic will be opened.

A good place for you to start would be the topic

|usr_07.txt|  Editing more than one file

Ok, on to your answer.

After starting vim with a list of files, you can move to the next file by entering :next or :n for short. :wnext is short for write current changes and then move to next file.

There's also an analogous :previous, :wprevious and :Next. (Note that :p is shorthand for :print. The shorthand for :previous is :prev or :N.)

To see where you are in the file list enter :args and the file currently being edited will appear in [] (brackets).

Example:

vim foo.txt bar.txt
:args

result:

[foo.txt] bar.txt

you can open another file while vim is open with :tabe filename and to switch to the other file you type :tabn or :tabp for next and previous accordingly.

The keyboard shortcuts gT and gt can also be used to switch tabs when you are not in editing mode (i.e. not in insert, replace etc modes). On some systems Ctrl+Alt+Page Up and Ctrl+Alt+Page Down also allow tab-switching, but this does not always work (for example, it won't work in the OS X terminal 'out of the box').

And you can see the filename at the top of the vim app.

Commands to switch between buffers:

:bf            # Go to first file.
:bl            # Go to last file
:bn            # Go to next file.
:bp            # Go to previous file.
:bw            # Close file.

:help buffer to find more information

To know filename use Ctrl+G,:file or :f