Other Controls Channels and layer masking are a mystery to me. I've never found a way to use them to improve a picture. Easy to make a picture look worse though, in many different ways. Web Photo Gallery Photoshop has a Web Photo Gallery creator on the File menu that will automatically convert a folder full of pictures into a little subtree, with an index page containing thumbnails and individual pages for each image. I post-process the output of this to change the HTML to my taste.
Some users run with images disabled or are unable to see pictures.
It is a courtesy to these users to provide enough text that they can at least navigate your page, and if the photographs are not the primary message themselves, to use ALT tags and descriptive text to allow them to get your message. There's plenty of information on the Web about this subject. Use a search engine to look for it. Carl Volk has a great set of tips , including some explicitly on the use of Curves and Levels. Tom Ruley has a diagram worth a thousand words about the relationship between Levels and Curves.