you need to make
after this in code behind you will have to access this tr and then add HTMLCell into this control
i.e
Dim cell as new HTMLTableCell
after this i think work gonna be clear to you.
just create table now, insert control into the table and table into the cell you just created.
i.e
dim ctrl as MyControl
dim tbl as new HTMLTable
tbl.controls.add(ctrl)
cell.controls.add(tbl)
Hope this will help you :)