K, managed to figure it out.
'Name' = Just a string for example 'Oppty1'
'OpportunityStage' = Browse some older already created opportunities to find default values. By default when you create a contact via Web2Lead it is 'Prospecting'
'Customer' = This relates to Customer table Name field (you used it in creation of customer)
'CloseDate' = just a date 2017-12-25
'AssignedTo' = This is CRM Method username that will handle these requests. You can find that in settings and users when you login to crm method.
I got one more question, now the opportunity is created properly but it as you can see in screenshot required field Contacts* is empty.
Is it possible to connect to