Execute the following command in the terminal, then open a new terminal window and the blender command should work as expected:
echo "alias blender=/Applications/Blender/blender.app/Contents/MacOS/blender" >> ~/.profile
What this command does is add the following line to the end of /Users/SteveW/.profile:
alias blender=/Applications/Blender/blender.app/Contents/MacOS/blender
I strongly recommend to not mess with PATH or any other environment variable for this, it only makes things more complicated, there's no reason to do so when you set up the alias correctly.