I have one data base named store and tables are order and firm fields are firmname,firmcode in firm table and orderno,orderdate orderqty,qtyrcvd and balqty are in another table. when selecting three combo box values (fetched from another table ) ie firm name , orderno and orderdate respectively when clicking a button check that it matches with the current value(current row values) in the order table if so fetch the result.
1.add the records in another table and result will be qtyrcvd is qtyrcvd, balqty is orderqty-qtyrcvd
please help me writing the code .I am new in vb.net

The first place to start is with some online tutorials. Search for VB.net tutorials and .net database tutorials. Once you have some code that needs help, someone will be more than happy to help you. This isn't a free-code-it site, where people will just donate their time and do the code for you.