How to use lower gears on the 2009 Toyota Camry LE?

I recently purchased an AUTOMATIC 2009 Toyota Camry LE. This car is NOT SEMI-AUTOMATIC but does have the lower gears of 4, 3, 2, and 1 under D. Is it okay to use these gears regularly to manually shift the engine? If so, at what rpm would you recommend shifting up and down?How to use lower gears on the 2009 Toyota Camry LE?No, it is not OK nor necessary; the automatic transmission was invented so that the driver need not manually shift the trans :]