Image Sizes, whick is which?

Good morning :)
I am having a small problem with image sizes and need some help.
For instance, in the config menu, there is a list of images.....small image, heading image, shopping cart image, image product listing, product new, etc etc etc.

Some of them are easy to figure out....just change the size and then look for what changes :) but others...not so sure.

Here is what I am trying to do:
On the front/main page, the categorie images and the "new for sept" images I want the same size. Preferably the same size as the new for sept. pics.

When you click on an item, it takes you to that items page....those are sized at 200x150....which is correct.

Then, when they click on that pic for a larger image....i want the larger image to be 400 x 300.

I have looked in the faq and do not see what I am looking for. Any step by step help would be much appreciated!! thank you!

Click on larger image automatically sizes to the image.

The 'larger image' images are displayed as-is. No resizing. Whatever you uploaded for your "large" image is what will display. If it's tiny, it'll be tiny. If it's huge, it'll be huge.

You will want to ensure that when you upload the "large" edition of your images that they are already sized appropriately.

Here's how small/med/large and additional images work:
http://www.zen-cart.com/forum/faq.php?faq=cats_and_prods#faq_add_images

thanks folks :) So if i understand correctly, i should upload all pics at the 400 x 300 size. This same pic will be displayed smaller on the new products section or will display at whatever size i choose in the images configuration.

So, if i upload the pics at 400 x 300, the smaller images are fuzzier and not quite as defined. I read something on the forum about fuzzy images, but did not quite understand (my brain does not work like it should sometimes:) )
could you go into a bit more detail for me?

Sorry for being so dense....my webdude is away and i am on my own :)

thanks again!

if you read the FAQ I mentioned, you'll see that you can upload SEPARATE images for each of small/medium/large.

If you load large images already sized appropriately, you won't have any problem.
Follow the FAQ for proper naming convention and directory to load them into