I'm working on Decrypting a "url" that some one gave me for a challenge but i dont know what to do anymore ^^
Maybe one of you can spot what i dont.

I already asked a Friend whos working with these things and he sayd it was easy but wont give me a hint^^

hsmRpcyaorZpbBtt/tevZ/.q:if/nEZ
2 5 9

Hints i got:
-"World War I, the Germans"
-"Not Math Included yet"
-"Its 2 5 9"
-"DCTC?"

What i tryd:

2RZ5BZ9EZ

8 19 13 18 16 3 25 1 15 18 26 16 2 2 20 20 20 5 22 26 17 9 6 14 5 26


   2+5+9 = 16
   2-5-9 = -12
   2*5*9 = 90
   2/5/9 = 0,0444444444444444


   2 = B
   5 = E
   9 = I


   ??
   RZ BZ EZ = GD XX AD XX AX XX
   ??


   Every 2 Letters
   = SRCARPBTTV/QI/E
   = 19 18 03 01 18 16 02 20 05 26 09 14 26


   Every 2 Letters Starting from the Last Letter
   = E/IQ/VTTBPRACRS


   Every 5 Letters
   = PRTV:E
   = 16 18 20 26 05


   Every 5 Letters Starting from the Last Letter
   = F//PYS


   Every 9 Letters
   = OTF
   = 15 05


   Every 9 Letters Starting from the Last Letter
   = .BP


   Letters Left = ifspybraventq
   = http://.com/


   Letters Left = smaorZbBvZqifEZ
   = http://encrypt./


   Letters Left = smRcyaZpBtvZqinZ
   = http://before./