Manipulate image src string toget thumbnail version

We urgently need someone to write some simple string manipulation code for a site admin pages. We need the job turning round in a couple of hours. You need to write a function to grab thumbnail version of an uploaded image string and write it to a text box The code must be in vb.net Please provide us with a single aspx and codebehind page with the following: aspx page - two textboxes, txtThumbnail and txtMainImage vb page - a function to rework the value of txtMainImage Functionality The code must check the contents of the text box txtThumbnail If it is empty, it must get the value of a second text box - textMainImage - and manipulate it as outlined below and then write the new value to the first textbox. You must find the last folder in the string and add another folder - /mcith then add the prefix mcith_ to the filename. Here are 2 examples: for the txtMainIMage value /Images/2011/Retail/Companies/Amazon/[login to view URL] the Thumbnail needs to be /Images/2011/Retail/Companies/Amazon/mcith/[login to view URL] Or with the main image... /Images/people/[login to view URL] the Thumbnail will be in /Images/people/mcith/[login to view URL] One final thing. Please write code to check that the first folder in the string is "/images/"