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:

google domains page


now go to the DNS page, should look like this:

dns page


go to the Custom Resource Records section and fill it out as follows:

crr


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):

subdomain forward

it may take a while for these changes to take effect. Enjoy!