How to Implementing Optimistic concurrency in code?

Question

hi,
I have posted the similar kind of question in post http://www.c-sharpcorner.com/Forums/ShowMessages.aspx?ThreadID=67505 but i dont this you have understood my problem:
Here is the scenario:
I have DAL that has a method

 

public DataSet GetAllProducts()
{   //code to return products

}

thsi will return a dataset that has a table of product data
I have another method

 

public int updateProduct(DataSet ds)

{

}

this will update the Products table.
In the front end i use a DataGridView.
in the bakc end i use stored procedure
Disegarding a seperate BLL and at themoment considering DAL as BLL
I need to implement Optimistic concurrency in my code, How do i do it? or please givem me links to find related information!
TY in adavance