Dear Afo,
My apologies I didn't knew that you wanted to open the file in brainstorm. Reading in files in brainstorm is relatively easy. I would suggest you to go through the first set of tutorials on the tutorial page about reading in files, I think that would help you a lot in using the fif files 
https://neuroimage.usc.edu/brainstorm/Tutorials
Kind regards,
Steven
Ps: Maybe this forum post about sensor organization might be helpful : Senors organisation - #3 by SAMOUSAI