If you just want to hyperlink a Web site address, type in the address
(you might have to start it with the http:// ) and hit the space bar.
PowerPoint should automatically turn it into a hyperlink. If you want to
hyperlink to an address but not have the address appear on the slide,
highlight the text (or object) you want to be able to click on, choose
Insert on the ribbon and then click Hyperlink. From there, you should be
able to set the URL for the hyperlink.