I just did this myself, found a very easy tutorial on Youtube.
You need to slice up the photoshop image (in photoshop), save as html & images, upload the images to imgur.
Open the html document in an editor (Chrome, dreamweaver, even notepad) - dreamweaver was the best cos of the preview but you may not have it.
You copy the imgur image url and paste it where the split images are in the html document. This is a basic overview, but as I said this Youtube video was very helpful for me, and pretty easy to follow:
http://www.youtube.com/watch?v=VrbOOmyOuzM
Hope this helps.