0 - 3 of 3 tags for order

I have a table that looks like this:

Column1 Column2 Column3
800 900 200
500 300 40
100 600 150

and I would like to concatenate Column1, Column2, Column3 in a list that is order by the values of three columns:


Please help me on this issue. Generally i want my recursice query to do the recursion by ordered. I want permutations from 2 column. See below.
1-Have this data
content_type, product_offered
0    2
0    5
0    4
0    6
0    1
0    3

Hi all
I'm new to teradata I want to confirm about the order priority of the execution of the query.
Sample query
Select top n x_column, y_column, z_column from table_abc order by x_column desc;
for the above mentioned query what is the order priority of the execution.