I'm new to Moodle development. I've been trying to find some information on creating a custom plugin.
What I'd like it to be able to do, is able to connect to a custom payment gateway (one provided by the university I work at). Once a student has made a payment through the gateway, the course then becomes available for them to complete in full. The courses will be set up in a way where the first section is "free" to view, but the rest is only available once payment is made.
I'd like some pointers to point me in the right direction. So far I've had a look at the Paypal plugin but I don't really understand how it does what it does.
Welcome to the Moodle dev game! A place to start is https://docs.moodle.org/dev/Tutorial and learn the basics.
Regarding the payment gateway I advice to look at the plugin directory https://moodle.org/plugins/?q=payment , there are several payment gateways already developed.
Best of luck!