what is the value of request.Headers["Authorization"] = "Zoho-oautht ......";

what is the value of request.Headers["Authorization"] = "Zoho-oautht ......";

Hi,
I trying to add account to zoho crm by using API, as below:
HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://www.zohoapis.com/crm/v2/Accounts");             
request.Method = "POST";             
request.Headers["Authorization"] = "Zoho-oautht ???????"; 

I want to ask what is the value of 'request.Headers["Authorization"]' should be ? and how I get it?

request.Headers["Authorization"]= ????