Here's your original request based on the column and table names you gave us:

select id, url, images, Total
from (
    select *
    from temp
    order by id desc
    limit 10
) last10
order by Total desc;
[download]

As for my pseudo-code you're confused about, that's only relevant if you have two tables that you might want to cross reference. As a more realistic example, suppose you have a database with Customers and Orders, and you want to find out your top ten buyers. You could do that like this:

  select Customers.name, sales.amount                     -- select na
+me and total amount spent. 
  from Customers, 
    (                                                     -- a sub-sel
+ect to find the 10 best buyers.
       select customer_id, sum(order_amount) as amount    -- This sele
+cts a column and an aggregate
       from Orders                                        -- from the 
+real table Orders.
       group by customer_id
       order by amount desc
       limit 10
  ) sales                                                 -- we name t
+his sub-select "sales".
  where sales.customer_id = Customers.id                  -- we INNER 
+JOIN the two "tables", 
                                                          -- so we can
+ cross-reference Orders against Customers.
[download]

As you can see, the "sales" sub-select isn't a real table in the database, but within this query we can treat it as if it were. We can select columns from it, and put extra constraints on it in a where clause. I hope it's a bit clearer now :)