By default, bash is configured to run in an emacs style editing mode. If you are more familiar with vi or vim, a vi-style editing mode is also available. (you can put this line in your ~/.profile if you are comfortable with it)
set -o vi
You will be in 'insert' mode by default. To go into command mode, press escape. If you try visual commands, you will go into vi/vim to edit the command. Write and quit to execute your changes (:wq).
If you stay in command mode without leaving bash, you will need to press an insert mode key such as 'i' to get back to normal typing.
If you want to return to emacs mode, type set -o emacs