How to append data to the second column

I have an excel sheet with data in the first column. I need to append data from a datatable to the second column of the same excel sheet. When I tried to use append activity, its appending data below the first column. How do I append data to the second column. I tried write range activity, but when I again run the xaml file, its over writing the data.

Extract the first column to a List A
List A=(From p in dt.Select()
Select Convert.ToString(p.Item(“FirstColumn_Name”))).ToList()

Then get the count of elements which are there in column 2
int b=(From q in dt.Select()
Select Convert.ToString(p.Item(“SecondColumn_Name”))).ToList.Count.

Now run one foreach loop for list a
1 Inside use one Assign activity
2.create one int variable int c and equate int c=int b initially
3.then use dt.Rows(int c)(“SecondColumn_Name”)=item.ToString
4. Then increment intc =intc+1
5. Finally if you want to display the datatable use writeRange

Here dt is your Datatable Variable.