mySql query, urgent help please

I have two tables:
Table one: user_name, address
(the user_name is unique)
Table two: user_name, prices
(this one allows duplicate user_name and prices)

I want to pick draw up a list of user_names with the highest prices. What is the correct way of joining the two tables?

If you don't need the address you don't need the first table.

select user_name,max(prices) as top_price from table_two group by user_name order by top_price;