To gat the total amount of all value showed in datagrideview

Sujit where you are facing problem you aren't mention properly.
As per your question i can understand that there is a form where you can enter 5 field value and rest of the 2 ie total and balance amount will be calculated and updated in the database.
Do it step by step and you can solve it by yourself then you can learn the project from your end.
If you are using SQL then check how to write SQLconnection string; if Access check OLEDB connection.

Next write insert query inside submit button code. You may apply some trick like while entering quantity write textchanged event and the total amount will be calculated as per text change. Try some validation like while pressing key that should not be char when it is quantity or Item price.
While update paid price write update query so that you record will be updated.
Now come to the grid section.
After entering records that should be displayed on some container you may use grid.
lots of events are there.
Lets start if you are facing any problem share with us.