Hi Nate_the_great
To edit your extlinux.conf file:
sudo vi /Path/to/your/extlinux.conf
vi has 2 modes, insert mode and command mode.
Press the i key. You are now in insert mode. Text will be inserted at the current cursor position.
You can move the cursor with the arrow keys and the Page Up/Page Down keys.
When you are done, press the Esc key. You are now in command mode. Depending on your needs, there are 2 ways to get out of vi:
:x<Return> Save changes and exit.
:q!<Return> Discard changes and exit.