I'm the only person I know of with this name. I'm often called Annette, Anita or Agnetha by people who seem unable to pronounce it. It is pronounced exactly as it is written!
"A" as in "Father." Pronounce both "NN"s distinctly-- most easily accomplished by placing added emphasis on the letter before ("A") and rolling through. "E" is quite nearly "Hey" (while excluding the "H"). Again, follow the previous instructions for the following double letters ("TT"). "A" as always, "Father." [noted -ed]