Anyways, that was a very good answer actually. Didnt think of anything shorter to say as usual.
lol
Ok.. so this is like a graphics program?
It's the industry standard html editor... generally used with photoshop, the industry standard graphics editor.
Why don't you head over to
www.Macromedia.com, and download their 30 day trial version of Dreamweaver? Sort of 'try before you buy', to get a feel for what it does.
edit: link for you:
http://www.macromedia.com/downloads/
Also, could I offer you one piece of advice? Well I'm going to anyway lol

Instead of using a massive image and slicing it up to a million little pieces, try using a layout, either in a table from a html editor, or a proper css layout, and use html background colors to save some of your images. That really cuts down your download times, and if your layout breaks it's easier to fix.