it is hard to tell you a hint without telling you the solution. it is also hard to solve without linux knowledge.
you should learn in level 2 how to hide things..
for level3: there are some files in linux with configurations, saving data, in your profile folder ;)
Contact only via c3BhY2VAd2VjaGFsbC5uZXQ= or PM...
Windows can be secure... but only if you don't use it