updates after class

lessons/lesson02.md

@@ -55,8 +55,8 @@ This tutorial works best if you are using the Bash shell. Linux and macOS come s
 * `rmdir DIRECTORY` — remove empty directory
 * `touch FILE` — create an empty file or change file modification time
 * `cat FILE` — print contents of file
-* `cat FILE1 FILE2 > FILE3` — combine two files into third file
 * `cat > FILE` — write to file
+* `cat FILE1 FILE2 > FILE3` — combine two files into third file
 * `cat >> FILE` — append to file
 * `cp FILE1 FILE2` — copy file
 * `mv FILE1 FILE2` — move file
@@ -76,6 +76,7 @@ This tutorial works best if you are using the Bash shell. Linux and macOS come s
 #### Working with commands and processes
 
 * `man COMMAND` — display manual page of command if it exists
+* `COMMAND --help` -- display usage information
 * `help COMMAND` — display help description of command if it exists
 * `which COMMAND` — show location of command
 * `history` — display past commands
@@ -100,7 +101,9 @@ For small jobs or if you want to stay inside the terminal, there are other usefu
 
 ### Setting up your bash environment
 
-There are several things you can do to set up your bash environment, which is what you see when you use the terminal (command line). You put these commands in a file called ~/.bash_profile (or ~/.bashrc or ~/.profile). That notation means the file is called .bash_profile (yes, that's a period, and the file is called a dot-file), and it's in your home directory.
+There are several things you can do to set up your bash environment, which is what you see when you use the terminal (command line). You put these commands in a file called `.bash_profile` (or `.bashrc` or `.profile`) in your home directory. Yes, that's a period at the beginning of the file, and the file is called a dot-file, which is a system file your computer uses to customize your shell.
+
+As an option, you can add the lines below to your `.bash_profile` using a text editor like Nano or Atom. Be careful to not overwrite what's already there, and to not add any extra commands or stray text. It's a good idea to save a copy of your existing `.bash_profile` with a different name as a backup.
 
 ```	
 # customize prompt with color and pwd