Many templates do not have built in drop down menus. Coding your own drop down menu can be an extremely difficult task for most people; fortunately, Joomla has several great extensions on JED for drop down menus.
Go to Extensions >> Extension Manager >> Browse... >> Upload & Install
Access Maxi Menu CK Module
Go to Extensions >> Module Manager >> Maxi Menu CK for Joomla! 1.6
Configure the Module
Select which pages on which you want the module to appear.
The rest of your parameters you can configure to your liking.
Congratulations! You just created a drop down menu in a matter of minutes. Now you can style the menu to your liking using the built in CSS files. If you don't know CSS, we have a great course on CSS in our coding class.