Hal8 it sounds like you are a new convert to the Mac. First of I would like to personally congratulate you and then tell you that it wont take you long before you are comfortable with the system. A lot of people moving over from a PC platform are confused at first just because they have gotten use to the "PC" way.
My New Friend, apostrophe made a comment about the Mighty mouse I would actually like to clear up.
The mouse that came with your mac (the Mighty Mouse) is actually a four button mouse. It looks like a one button and is set up by default as a one button but by making a few adjustments in your System Preference you can have up to a four button mouse with up down and left right scrolling.
Here is how you find that menu. (If you are not new to mac please forgive the assumption )
Click on the area highlighted in blue.
The mouse set up is pictured with a keyboard and looks like the icon in the bottom right of the image below.
Click on the icon mentioned.
You will be looking at a menu bar where you can select and set up personal preferences for your Keyboard, Mouse, if their bluetooth settings and keyboard shortcuts… For this you would want to obviously select the mouse option.
This image is how I have my mouse set up. Secondary button is like right clicking.
There you go… I know it wasn’t part of this post topic but if you are an avid photoshop user you will find that this is can make your life a lot easier and fast for common task you do in Photoshop.