Hi
Here is the learn website for the me Orion board.
Here is the link to guide install Arduino software and Makeblock library.
After you added the makeblock library for the arduino software, you can see many examples for the Orion board, you should be able to find some program related to use the I2C too.
According to above example program, you can see that if you have a electronic module with I2C address, no matter which port on me Orion board you connect the module to, you just need use the I2C address to look for the electronic module in arduino program, no need to tell which port to use.