HIB with Incorrect citizenship country name

I am living in USA since last 2-year on TN-Visa.
This year I applied for H1B-Visa, and I got my H-1B approval paper on last week.
In my H-1B Approval notices(I-797A)I-94: states that "my country of citizenship is My Birth Country, instead of Canada".

My Attorney told me that it is not a big deal, It can easily be corrected upon my request and show my Canadian-Passport to Customs & Border Protection Officer on my next trip at Border/or Embassy. and officer will change my Country of Citizenship to Canada.(I was apply H1B-visa on my Canadian Passport)

Q1). Where I go to stamping of my H1B visa. (it stamp on Canadian Border or I book an appointment in Vancouver-USA-Embassy).

Q2). My Friends tell me that at Border or Embassy, its very difficult to change anything, like here Country of Citizenship".

IS anybody face same kind of problem?

Q1). Where I go to stamping of my H1B visa. (it stamp on Canadian Border or I book an appointment in Vancouver-USA-Embassy).

You don't. You are a Canadian citizen so don't need H1-B visa stamping.

Q2). My Friends tell me that at Border or Embassy, its very difficult to change anything, like here Country of Citizenship".

I believe that they often just put 'country of birth' in the field for 'country of citizenship'. Perhaps this is because of the dual intent nature of the H-1B and a desire on their part to document the country of chargability for GC purposes (usually the country of birth, not citizenship). Regardless--there is nothing to change here. Just use the approved H-1B noting the country of birth and use your Canadian passport.

The only point where there would be an issue would be if you were born in country A and are trying to travel to country B and country B doesn't like country A. However, that doesn't seem to be your situation.