This link will help you find out what districts you are in. It's as easy as 1-2-3!
Type in your address in Shelby County.
Include the city after the address. (123 Main Memphis for example.)
Click on the little blue square to the left of the box that appears in the center of the screen. Hit the + sign in the upper left hand corner of the screen several times to zoom in. This will make sure that your cursor is actually on your address.
Shelby County Election Commission District Locator