Xperia M5 Marshmallow update with flash tool

I'dlike to update my Xperia M5 to marsmallow i tried with Xperia companion app and it showing everything is up to date but i has 5.1 lolipop I think it still not availalble in my country so if somone can make some video tutorial about flashing with flash tool because i never done this before so I afraid of bricking my phone :rolleyes: in question is E5306 model

P.S Sorry for my bad English :D