how to take DataSet Value into an variable

You can set particular cell value of dataset into variable. like this

string name= Convert.ToString(ds.Tables[0].Rows[0]["name"]);

or

string firstrowvalue = ds.Tables[0].Rows[0][0].ToString();

string secondrowvalue = ds.Tables[0].Rows[1][0].ToString();

string thirdrowvalue = ds.Tables[0].Rows[2][0].ToString();

using loop you can iterate values in the variable or if you are binding values into data binding control then also do the same :

int value=0;
for(i=0;i<ds.tables.rows.count;i++)>
{
  int value=value + Convert.ToInt32(ds.Tables[0].Rows[0]["value"]);
}

Hope this will help you.
And don't forget to mark as answer if it helps. :)