Id  Value
1   football
2   Tennis
3   Cricket

var dataTable = dataSet.Tables[0]; //For this example I'm just getting the first DataTable of the DataSet, but it could be other.
var id = 1;
var value = "football";

//Any(...) will return true if any record matches the expression. In this case, the expression is if a Id Field of the row is equals to the provided id
var contained = dataTable.AsEnumerable().Any(x =>x.Field<int>("Id") == id);

if(!contained)
{
    var row = dataTable.NewRow();

    row["Id"] = id;
    row["Value"] = value;

    dataTable.Rows.Add(row);
}

DataRow newrow = ds.Tables[0].NewRow(); //assuming ds is your dataset
   newrow["id"] = "your new id value";
   newrow["value"] = "your new value";
   ds.Tables[0].Rows.Add(newrow);