Hi Saudra,
Spreadsheets aren't easy for most people. Here you can do something like this:
To your imported table you add an extra column:
Convert your first row into a Header Row (that's important in Numbers).
Add your formula into row 2 (first row that is not a Header Row) of the column you just added (I've named it Sort).
"Fill" that formula down through the rest of the rows of the new column by dragging the yellow handle.
Sort on the new column:
And you've got your sorted table:
To change the order by which you select columns for the sort just adjust the formula in D2 and fill down again by dragging the yellow handle.
It would be much nicer to have this built in the way it was, but this is not that complicated once you've done it once or twice.
SG