You have to read the excel sheet first and then store it in a datatable variable dt
then after copying the selected text you can assign to the excel sheet by using Assign activity dt.Rows(index of row)(column_name)=copiedText
else
1.By using Build datatable activity you can build a datatable dt.
2.After that use Add DataRow activity to add the values.
3. At last you can write in excel sheet by using write Range activity.