Quite alot if you want the windows forms to actually open from a page or link on a user's web browser. You'd have to either; convert the VB standalone application to an ActiveX application, and use that on the webpage, but be warned, clientside ActiveX only works on Microsoft's web browsers and VB only really works under Windows. Still, you could convert the application in that way very simply; since you could reuse pretty much all the code with a few changes at the entry point of the application; and then add it to webpages with a tiny bit of ( MS only ) HTML code.
If the application isn't meant to be run at the user's end; i.e. it's a server application; then, I have no idea. I've never used a Windows server for anything more than HTML/basic ASP... but I'm sure it's possible to configure and use a VB app as a server program. It's certainly possible to write DLLs that can be used from other MS technologies, so, you could write a DLL in VB and perhaps use it from ASP... The user ( infact no-one ) will see the pretty forms though.
This Visual Basic 2005 app is basically a wizard that starts out with a background image. Then the user selects a number of images to overlay it producing a final image that is saved for later retrieval, and can be printed or emailed.
The 'other' images are .png files with transparent backgrounds.
Can the vb.net code be installed on the web server and executed from a browser as an internet app or does it have to be rewritten and, if so, in what language?