echo "Choose an option, 1-4."
read Option                  #User's keyboard input is stored in variable "Option" (this is a comment, and is ignored by  bash)
if [ $Option -eq 1 ]   #if the input in variable Option equals 1...
       then
              echo "You have entered ONE!"
       elif  [ $Option -eq 2 ] #be careful here! if you put an 'if' here you create a "nest," if statements within another
            then
                  echo "You have entered TWO!"
       elif [ $Option -eq 3 ]
             then
                  echo "You have entered THREE!"
       elif [ $Option -eq 4 ]
             then
                  echo "You have entered FOUR!"
       else #you could just skip it, as it isn't neccessary for the menu, but it's fun!
             echo "What the hell is wrong with you? Is it too hard to enter a valid number?"
fi #so bash knows the if statement is over. If you forget this, all code below this will belong (and only execute if it is true) the first if statement (if [ $Option -eq 1 ]...), which will lead to debugging hell, if this wasn't intended)

echo "Choose an option, 1-4."
read Option     
case $Option in      #initialize the case statement
       1)          #if you entered one, do this
                echo "You entered ONE!"
                ;;    #so bash knows the first case is done.
       2)   
                echo "You entered TWO!"
                ;; 
       3)   
                echo "You entered THREE!"
                ;; 
       4)   
                echo "You entered FOUR!"
                ;; 
       *)       #like the statement "else"
                echo "What the hell is wrong with you? Is it too hard to enter a valid number?"
esac   #so bash knows the whole case statement is done. if you don't do this, it gets even more hellish than if you forget "fi" in an if statement!