Take a look at this post: 400th anniversary of Shakespeare's death

https://community.wolfram.com/groups/-/m/t/842698

I recommend searching this forum, documentation, Wolfram blogs and other sites. There is a lot of useful information already published.

Try WordCounts instead of WordCount. For instance, if myGatsby is the variable holding the text of the book as a string, then you could use

WordCounts[DeleteStopwords[myGatsby]]

which produces an association whose keys are the words and whose values are their frequencies. In the copy I downloaded from Project Gutenberg Gatsby appears 199 times and Daisy 150 times.