Create a trial account inside LeadsBridge platform here
Head over to the left sidebar and click on Integrations
Click on the Add New button
Enter a recognizable name for your integration
Click on the Browse button
Select 'Zendesk Sell' from the providers list
Click on the Next button
Select the entity concept you'd like to use (ex Lead, Contact, Deal) as explained here
Select the segmentation concept you'd like to use (ex Tag, Lead Source, Deal Phase) as explained here
Click on the Authorize button
A Zendesk Sell's wizard will popup
Enter your credentials and grant the access to LeadsBridge
Head back to LeadsBridge and click on the Finish button

LeadsBridge