I can only guess as to why your putting it in Public_html was successful. My guess would be that you and I likely have different DreamHost plans.
On the pictures...
You will need to FTP the all of the picture files as well.
But it may not be that simple, depending on the way the HTML is pointing to the picture.
If the HTML simply has the file name (i.e. "picture.jpg") for a path, then all you have to do is FTP the picture files to the same directory as the HTML file.
But some times the HTML is point to an absolute (or full) path. If the absolute path is to your hard drive (i.e. "C:\My pictures\vacation\picture.jpg") then it will never work from the web for anyone but yourself. So you will want to edit the HTML so that the path contains only the file name.
If you want to get more advanced...
You can point the HTML path to a different location on the web (usually within your website.)
For example, you could create a subdirectory inside your "Public_html" directory called "images". Then in your HTML the path to the picture would be, "./images/picture.html." (Without the you-know-whats)
What does the path mean?
the leading "." means the present working directory (a.k.a. pwd). So the HTML say, 'from this directory find the "images" directory, inside "images" open the "pictures" file.
Leading with the "." in known as the relative path. What is nice about using that in your site is that it makes your site portable. All you have to do is move/copy the parent directory to anywhere, and it will still work.
You can also lead with "../" which means to go back one directory. But thats another story.
YOU HAVE BOTH a simple file name and a relative path.
The first one is:
This means that you have to have a directory inside "Public_html" called "index_files". And insided "index_files" you need to put your "image001.jpg" file.
(personally I would also put a "./" before the "index_files", but that's just me.)
The second one is:
The code is not what I am used to, but I do notice that there is a space. The internet does not like spaces in file names (neither do I). You can usually get around that by enclosing the file name in quotes. Or, you can rename the file to "drivers_license.jpg" and then change the HTML. But the path is in the same location. So you should only have to FTP the "drivers license.jpg" file to the "Public_html" directory.