How to automate logging PayPal transactions to google sheets like Zapier?

My scripting/web app know-how isn't the best so please bear with me. Currently I use Zapier for my small business which automates the process of adding a new row to a google sheet whenever a successful PayPal transaction is triggered. Each row in the sheet contains the following information:

transaction id (unique), first name, last name, email, amount paid, class, class id, date paid

I love the ease of being able to use Zapier for this, but being a small business, I'm trying to minimize such expenses. I'm wondering, is there anyway I can code up something that does what Zapier does and where would I even start? This would be a great learning experience more than anything. Any help would be appreciated. Thanks in advance!