I filed federal tax extension thru Turbotax online. How do I get the details or the proof of the extension, that I can use for my state extension as well?

You should have received an email updating the status of the submission. That is your proof. 

so we never noticed until this year that Alfred name was spelt wrong through ss office and it took this long for it to get fixed because we could not go in office so know i would like to proceed with filing this year ane last year taxes

To file the 2019 return log in and complete the FILE tab using a single ZERO for the 2018 AGI since the 2018 return has not been filed yet.

To file the 2018 return you must print, ink sign and mail in the return.  

Yes it did. However it is generic and to my email address. I am not one who extended the return, but I filed extension on behalf of my son. The email does not relate to it in any way.