Rhino has a very flexible and customizable interface. You can start commands three different ways depending on how you like to work.
You can:
Use the pull-down menu.
Click a toolbar button.
Type a command at the command prompt.
Click the command name to popup a chart that shows the button, the command name and the menu location. Soon you will find a method that suits your style.
Use the method you like best to activate the command.