first things first, you want to add the domain to heroku by typing the following into the terminal, im using leaguefrenzy.com as an example:
$ heroku domains:add leaguefrenzy.com
$ heroku domains:add www.leaguefrenzy.com
its a good idea to add leaguefrenzy.com as well as www.leaguefrenzy.com
First, purchace a google domain here.
after going through the purchace process, you want to be at a page that looks like the following:
now go to the DNS page, should look like this:
go to the
Custom Resource Records section and fill it out as follows:
lastly you want to add a subdomain forward so if someone types in example.com it will forward them to www.example.com (you need to put an @ sign in the subdomain field):
it may take a while for these changes to take effect. Enjoy!