how to give text to the Templated Image File in asp.net?

Hi All,
I want to make a logo design web site.
for that i created some predefined images(cerated some logo and text effect).
now i want to give text from asp website to that predefined image file and i want to display that image on page.
for example 
http://www.designmantic.com/index4?utm_expid=68723407-5.xTGHOToNQeqU8ErIfXYzcw.1&utm_referrer=https%3A%2F%2Fwww.google.co.in%2F
in the above link
when i enter text in textbox and click on show my design button then
it will show  my entered text on that image(the text will be appeared with that design)
how can i do that task(same functionality like above link)

Thanks,
Murali.