I am trying to create an integration in salesforce that will send contacts to Zoho CRM.

I see the trailhead (https://trailhead.salesforce.com/en/modules/apex_integration_services/units/apex_integration_rest_callouts) talks about REST Callouts, but not sure how to send contacts to Zoho CRM. I created an account on the site but the google searches, docs, and vids always seem to point to using a tool like BedrockData. 

Not sure really where to start. Do I use this to connect to zoho? request.setEndpoint('https://crm.zoho.com/crm/private/xml/Contacts/???');
and  request.setMethod('POST'); ?
and then in  request.setBody(  <--- I put the fields for the contact?
I don't see where to put the API key? [also is this where I get it in the first place ? https://crm.zoho.com/crm/ShowSetup.do?tab=webInteg&subTab=api&action=developerapi ]