Once I had produced my images in photoshop at 72 dpi, because that is the resolution needed for a website compared to printing which is normally around the 300 dpi.
Then I had to save them for web and devices which in the end opened up this screen, what you could do was go through the different files such as JPEG, PNG AND GIFF.
Then you would have to look and see what gave best results, but at thesame time how much time it took to upload. So once I had decided on these images it was time to get them up as a file format, I normally chose 4 up to view them. This gave me a 4 way split screen and I could see the original and then three others at different quality percents. Really you shouldn't go under 60 otherwise the quality isn't there and for photography that is not good.
Once I was happy with that, I decided to save them and name them appropriatley and this allowed me now to open in dreamweaver and use the image with ease.