Bash is an incredibly powerfull tool that will increase your productivity. It might take an investment on your part, but it's well worth it. This guide is by no means exhaustive, it only shows you the basics.
Assuming your on linux, go ahead and launch a new terminal session. This is starting what is called an interactive shell. Both its standard input and output are connected to the terminal you just launched. Standard input or stdin is the source of input data for command line programs. Standard output on the other hand is the data that is the result of a command.
When you frist startup a terminal, your ~/.bashrc file is executed. Go ahead and modify your ~/.bashrc file so it looks like the following:
echo "Hello world!"
Now start up a new terminal. You should see Hello world! in the terminal.
Lets look at the ls command. This simply lists all the files in your current directory. When you start up a new terminal it will put you in your user's home directory. If you run ls -a it will also list files that start with a ..
The cd command will change your current directory. cd ~/ will take you back to home directory, cd .. will take you up one directory, and cd - will take you back to the previous working directory. Simply run cd <directory> to step into a directory
Typing commands and filepaths can be cumbersome, so let's learn some keyboard shortcuts to help us be more proficient.
Use tab to autocomplete commands and arguments. Especially useful when trying to type out file paths.
The up and down arrows will cycle through previous commands. You can also run history to see all you recent commands.
ctrl+U will clear the entire line.
ctrl+K will delete all characters on the line following the cursor.
ctrl+R will search your command history. Just start typing to search for previous commands that match your search term.
Sometimes you need a quick way to edit a file from the command line. The easiest way to do this is by learning a command line editor. vim is extremly popular, but can be frustrating for new users. Lets look at some vim basics:
When you first enter vim you will be in normal mode. You can't edit any text at this point. You need to be in insert mode. Simply type i to enter into insert mode. Now you can edit text. To get out of insert mode hit the esc key.
Navigating vim can be awkward at first. You need to be in normal mode to navigate through text. You can either use the arrow keys or h j k l. Once you get used to using the letters, it's extremely efficient.
To exit vim you need to be in normal mode. Type :wq to save the file and exit vim. You can use :q! to exit without saving. :w will save file, but will keep you inside vim.
If you want a more in-depth tutorial run vimtutor on the command line.
If you want to view the contents of a file, you can use less <filename>. This will allow you to page through the contents of the file. Use page up and page down to navigate. Type q to quit.