Hi Rising,
Thank you for your question.
1. I am using Exchange 2013 SP1 i want to customize OWA web page, please do guide me how to achieve this
A: we could refer to the following link to customize OWA web page:
https://technet.microsoft.com/en-us/library/ee633483.aspx
How to configure Send and Receive connectors in Exchange Server 2013 SP1. Please do share any screenshots so that i can cross check if i am making any mistake.
A: We could refer to the following links to create a send connector for email sent to the Internet:
https://technet.microsoft.com/en-us/library/jj657457(v=exchg.150).aspx
We could refer to the following link to create a receive connector:
https://technet.microsoft.com/en-us/library/aa996395(v=exchg.150).aspx
In addition, after we install Exchange 2013, we could send/receive email in organization. If we want to send/receive emails to/from Internet, we could create a send connector and receive connector:
Send connector:

Receive connector:

If there are any questions regarding this issue, please be free to let me know.
Best Regard,
Jim