When you talk about your uncles or aunts (your parents' brothers and sisters, or the brothers and sisters' wives or husbands), you can name them like this:

I talked to Uncle Remy last weekend.

We went over to Aunt Jean's house for dinner.

If the person who you're talking to doesn't know your aunt or uncle, say "my Uncle ___" or "my Aunt ___":

My Aunt Joni is the president of a big furniture manufacturing company.