Open the trunk. In the left corner where the lamp assembly is, you should see two screw covers that cover the screws holding in the lamp assembly.
Remove these covers to find the screws, and unscrew them to pull the taillamp assembly out of the vehicle body. Disconnect the lamp wiring harness, turn the bulb socket counterclockwise to pull out the socket, revealing the light bulb. Then pull the bulb right out of the socket and replace it with a new bulb.
Replace the socket, turning it clockwise. Replace the taillight assembly. Check that the taillamp assembly tab, located at the bottom of the taillamp assembly, is aligned to the facia bracket before securing the screws.
Screw the taillamp assembly back into the vehicle body and replace the screw covers. Check to make sure the new bulb works properly.
Your owners manual specifies that the rear left turn lamp is a lamp with bulb number 3057K. You should be able to find them at any automotive store or from your dealer. Hope this helps.