catholic question

Hello OBOB, I am currently waiting for my parish priest to return in about a week so that I can begin my instruction to be able to join the Catholic Church. I have settled every issue I had with it (mostly my pride in rejecting teachings I didn't like, as if I were God), although I do have one...

I have a question about buying and selling on Sundays, buying food, and buying things from a special fair on Sunday are exceptions to the Third Command correct? Because I might have done both of these things in the past, albeit, without realizing them.