please help. webdiff. fuzzzy ..in deep trouble

question. please please help. I need to create a diff ... I can use all the unix commands there is to make. I need to make this webdiff that will diff (unix diff) between local and remote files such that with -m option it Ignore a fuzzy change. Does a smart check of whether a page has changed based on word counts. Compares after removing the top 10% of the common dictionary words and considers files to be different if
more than 5% of the words have changed in their counts.

any ideas please? can anyone help me to start with? I am very begineer with scripting...