how can I get all of the tables from http://www.imq21.com/market/summary this website? should I using DOM HTML?
Literally, you cannot get all the tables easily.
However, the table of that web site is not a flash. thus you can GET the entire raw HTML of that site, and applying Regular expression to parse the item one by one, and create your own class to store the output, and add the fetched data to the table your wanted.
Note:
it is not an API, thus you need to visit another link for another table and apply the same technique (Fetch HTML, regular expression, manipulate the data and store in the table) for all tables that you needed.
it maybe illegal or not regular to fetch data from other web site like that :D ... and if it is owned by you, you can simply write an API for your program to fetch the data directly (faster, and relatively lesser amount of work)