Best way to do it by downloading a program called Hamachi.
www.hamachi.cc
whoever plans on playing the network game, they all need to download this, only takes 2 mins.
Then follow hamachis instructions and whoever the host of the game will be needs to set up a network on there and get everyone to join it.
Then open fm10 up and start network game, tick run as server and then when its loaded up, whoever is playing needs to go on join network game and put the isp that shows up on hamachi into where fm asks you.
Then, bobs your uncle.