How to add Register option in Yahoo Store. I am new to this. Please help me step by step?

That's a great question and we do have a step by step help page on how to set up the registration option on your store. Check out:

help.yahoo.com/l/us/yahoo/smallbusi...

Also, if you have any other questions about the setup or need help with any other part of your Yahoo! Merchant service, feel free to contact us at smallbusiness.yahoo.com/contactus/

Source(s):

help.yahoo.com/l/us/yahoo/smallbusi...
smallbusiness.yahoo.com/contactus/