How to test Javascript implementation of SHA256 against real block, real nonce

[darius2020]

Hi,

I would like to learn more about Bitcoin's black hashing.

I have downloaded javascript implementation of sha256 fit to be run under Windows XP
http://www.movable-type.co.uk/scripts/sha256.html

I need to verify it against real data
and modify to accept new block of transations as input and  nonce as input
and hashed value as output in graphical form

I don't know how to get a new block what app run to hash Merkle tree to get single hashed value
as input into sha256 + time

Could you help me with basic, step by step manual ?

darius