Hello again to You all:
Thank you for all the help you've been given here.
This time I'm posting how to do it instead of asking it.
If you want to select a specified column with a basic code:

ActiveDocument.Tables(1).Columns(4).Select 'select column 4 on
table 1 in this document
With Selection.Find 'find and replace text applied in all document
and column 4 only
.Text = "Aunt Gee is eating Cozido"
.Replacement.Text = "Aunt Gee is eating Tripas"
End With
Selection.Find.Execute Replace:=wdReplaceAll

Hope this can help some one.
Bye.
Abel.