my_text=“This is the first sentence and the second sentence doesn’t
exist”
words=my_text.split(" ")
my_hash=Hash.new(0)
words.each do |w|
my_hash[w]+=1
end
my_hash.each do |k,v| puts k+" "+v.to_s end
#I need edit this code to read information from more files in same
folder
I’m guessing you need my_test to be equal to a file’s contents. Do you
want it to be a single string formed from multiple files, or do you want
1 Hash per file?
Also, your current method doesn’t allow for punctuation and is
case-sensitive. Here’s an example of a Regexp which could improve it,
although you can’t account for every possibility 
http://www.rubular.com/r/WHWt6Nw4Pd
The first thing you need to do is try for yourself. There no shortage of
examples of reading text files, and you haven’t even tried to do that.