How do i use over drive in my 2004 Automatic Toyota Rav4 2wd?

I have a 2 wheel drive 2004 Toyota Rav4 with an automatic transmission. How do i activate overdrive so that the engine speed reduces and the fuel economy increases? Is it ok to use overdrive daily? I know that there is a switch next to the drive shaft that says overdrive. Thanks in advance for all help.