How do you train to become a sniper at home?

You cant at home but In the British army you ask for a course which is 9-8 weeks long depending where you do it. 1 week of lectures ( history ) tailoring your rifle and your Gillie suit fitness, 2nd week short 0-300 to mid 300-600 range shooting and test 3rd week long shoot and test 600-1100 4-8 week is exercises and skills training , camouflage and concealment, stalking , judging distance , map reading , navigation exercises and observation week 9 is test week on all 6 sniper skills including a written test.

ex army sniper six years Iraq and Afghanistan