Question

How do I manually add new rows to a datagrid?

Answer 1

You should not add rows to datagrid. You should add rows to object (collection, datatable) bounded to datagrid.

DataTable dt = new DataTable();
dt.Columns.Add("Name");
dt.Rows.Add(new[]{"John"})
datagrid.DataSource = dt;
//Adding new rows - simply paste this code into (for example) button click event handler
dt.Rows.Add(new[]{"New John"})
//And you should be able to see new row added to grid

Also there are number of commercial grids that supports unbound mode.