I only have basic skills...and hoping for any help on a problem

I can get a Deal record just fine, but it doesn't return any related deals for that record (we have a custom field setup which is a link to another deal)

I assume this is what the related lists API is for, but I don't understand it's usage

the example code in the api docs shows: https://www.zohoapis.com/bigin/v1/Contacts/410888000000698006/Notes

what would be the syntax to return related deals?  when i try https://www.zohoapis.com/bigin/v1/Deals/[dealID]/Deals it just errors out??