Welcome to Level 13.

Spoiler:

Like we always do,check the page source.
The hint we will get is :

-Friday
-13
-Black Cat
-The Date
dd/{mm}/1949 1st
dd/{mm}/1984 2nd
dd/{mm}/1946 2nd
dd/{mm}/1955 1st
dd/{mm}/1937 1st
dd/{mm}/1981 3rd

So what we need to do ?
The thing we need to do is "find the date"

With the hint Friday and 13 we already know that we must find the month of

Friday 13/mm/1949
Friday 13/mm/1948
Friday 13/mm/1946
Friday 13/mm/1955
Friday 13/mm/1937
Friday 13/mm/1981

But what mean the black cat ?

The Black Cat mean Night.

If we think properly the date we need to find is "12th thursday night".

So let's find "The month of Thursday 12th of year 1949,1984,1946,1955,1937 and 1981".

Lazy to find ? click the spoiler :

Spoiler:

Now you get the month.
Check back the hint.
dd/{mm}/1949 1st
dd/{mm}/1984 2nd
dd/{mm}/1946 2nd
dd/{mm}/1955 1st
dd/{mm}/1937 1st
dd/{mm}/1981 3rd


Arrange the month.You will get the answer.

Still stuck ? Click spoiler :

Spoiler:

I think you already now what you must do for go to level 14.
If still stuck click spoiler.

Spoiler: