To learn more about security etc, I'm doing all Internet challenges I can find. Unfortunately I always get stuck. This time i need to decipher a text.
I've read a lot articles about: Caesarís box, mono alphabetic substitution etc. But now Iíve encountered a text and I donít know where to begin.
I've tried to replace all the letters 26 times, according to the Caesarís box. But that doesnt seems to work.
And i also tried the mono alphabetic substitution method, but that doesnít seem to work either.
And according to the challenge it must be really easy....
Here is the text:

Gsv kzhhdliw gszg blf mvvw rh gsv mznv gszg
yvolmth gl gsv nzm gszg hzbh gsv mvcg hvmgvmxv:

"Givzg blfi kzhhdliw orpv blfi gllgsyifhs.
Wlm'g ovg zmbylwb vohv fhv rg, zmw tvg z mvd
lmv vevib hrc nlmgsh."

Could someone please give me a hint of what to do and how to proceed? (Not the answer)

Thank you.