PLaceholder control

Hello,I take one label &textbox & 1button as in asp.net dragdrop. i want to generate another control at runtime hence placeholder is use.another control i.e textbox i want at runtime that can be run at button click.but seen only see at once i want as many time click that many time that controls may come .same one run time button i create on click it also show some textbox & label .it show only at once when all this call at page load event.but i want at button click what can ido? please help me.