learning auto-implemented properties

i have rudimentary category controlling auto-implemented properies:

public category foo
{
    open foo() { }  

    open twine barname {get; set;}
}

i apparently non-static barname via category need supplement explanation ability value set (it contingency top case, figure). does meant i need emanate private non-static barname , e.g. _barname, change tide barname non-static used via category _barname?

public category foo
{
    open foo() {}  

    private twine _barname = "";
    open twine barname 
    { 
        {return _barname;}
        set {_barname = value.tostring().toupper();}
    }
}

i am perplexing certain i know implications controlling auto-implemented properties, entail down highway when/if i need change something. i am presumption refactoring, shown above, change since ability fundamentally staying same; only took small work inside category keep proceed supplement indispensable logic.

another example, competence some-more revealing i need slight setter getter used; some-more following changing value.

this seems satisfactory trade off the lines lines formula setup properties.