This is so trivial. You can see the complete tutorial to solve it in the webinar (which I didn't see until I finished all the challenges). The only thing I want to show here is that I solved this using objdump, I didn't have access to Windows when I downloaded the first challenge:
objdump -p -s -d i_am_happy_you_are_to_playing_the_flareon_challenge.exe
I know its not easy to read it, and it didn't occur to me to use online disassembler, but with a bit of concentration we can immediatelly see that push $0x4020f2 refers to the string "Let's start out easy\r\nEnter the password>". Address $0x402158 will contain the result of ReadFile, and it will be compared with block at 0x402140 after xoring it with fixed key 0x7d. So basically this is just XOR encryption, 24 characters ("cmp $0x18,%ecx").
objdump -s --start-address=0x402140 --stop=0x402158 i_am_happy_you_are_to_playing_the_flareon_challenge.exe
And this one line of python is enough to solve it:
print "".join([chr(ord(x) ^ 0x7d) for x in "1f08131304220e114d0d183d1b111c0f18501213531e1210".decode("hex")])