1. Login to your master reseller WHM

2. Access the MR Panel - Intergration tab

3. Please download the WHMCS Intergration software to your local end.

4 . Upload the file "whmphp.php" to your /modules/servers/whmphp/ folder of WHMCS
    (Create the folder whmphp if required)

5. Create a new server from WHMCS Admin Panel ( Setup - > Servers ) and
   select "Whmphp" from the server list. Enter the following Details

   a. Server Name
   b. IP address
   c. Your Master Reseller username
   d. Your master reseller password
   e. Nameservers ns1, ns2 and its IPs

   All other fileds are not compulsory

6. Now create a new Reseller Package from Setup - > Products/Services and
   assign the package on the newly created MR Panel server.

You are done!

According to the auto-setup setting for your WHMCS, when you receive an order for
Reseller account, it will be processed automatically and the user will receive  the
welcome mail.