I don't see where your problem is.

You have been given a detailed algoritm, so your problem must be with implementing it.

Is it with making the HTML-form? If so go and check some basic documentation on how to write a HTML-file.

It can't be with the flatfile database text file, the instructions are clear.

Is it the search script? Check the CGI.pm module about getting form-input. For reading a file into an array, check the perl-docs about the diamond-operator (<...>) (HINT: use two arrays, one to hold the movie titles and another to hold the reviews. Or use a hash with the key being the movie title and the review as the value, but then be very sure that there are no duplicate movie titles in your database).For outputting the results into an HTML file, again CGI.pm comes to the rescue.

That should put you on your way. Let us know what you made of it!