Can't find my photoStream pics in folders.

Question

Summary:  When I'm trying to upload photos to some other application or online picture service I can't find the folders where my pictures are located. 
Facts:  I'm using iphoto (importing from camera) and photostream (importing from iOS devices) to get photos on my new iMac.  I'm new to using Macs.  Many uploading and importing services and applications are folder orientated. 
Challenge:  Let's say I'm playing with Google's theme's creator and I'm trying to upload pictures to create my own theme.  I can't navigate to a folder on my iMac where I can choose photos to upload, especially PhotoStream photos. 
Ancillary Questions:  How or where should I be saving my pictures to be able to upload them to any service I wish?  Should I not be using iPhoto to import photos?  What about Photostream?  I love the "sharing across all my devices" aspect, but if that saves them to a Never Neverland database that's not cross-referenced to a folder that I can access -- what to I do?
Thank you,
BeeBitten

Answer 1

Required: A moment to learn how to use iPhoto. 
It's a database and it provides a lot of hooks for accessing photos to use in other apps and services.
There are many, many ways to access your files in iPhoto:   You can use any Open / Attach / Browse dialogue. On the left there's a Media heading, your pics can be accessed there. Command-Click for selecting multiple pics.
(Note the above illustration is not a Finder Window. It's the dialogue you get when you go File -> Open)
You can access the Library from the New Message Window in Mail:
There's a similar option in Outlook and many, many other apps.  If you use Apple's Mail, Entourage, AOL or Eudora you can email from within iPhoto.
If you use a Cocoa-based Browser such as Safari, you can drag the pics from the iPhoto Window to the Attach window in the browser.
If you want to access the files with iPhoto not running:
For users of 10.6 and later:  You can download a free Services component from MacOSXAutomation  which will give you access to the iPhoto Library from your Services Menu.
Using the Services Preference Pane you can even create a keyboard shortcut for it.
For Users of 10.4 and 10.5 Create a Media Browser using Automator (takes about 10 seconds) or use this free utility Karelia iMedia Browser
Other options include:
Drag and Drop: Drag a photo from the iPhoto Window to the desktop, there iPhoto will make a full-sized copy of the pic.
File -> Export: Select the files in the iPhoto Window and go File -> Export. The dialogue will give you various options, including altering the format, naming the files and changing the size. Again, producing a copy.
Show File:  a. On iPhoto 09 and earlier:  Right- (or Control-) Click on a pic and in the resulting dialogue choose 'Show File'. A Finder window will pop open with the file already selected.    3.b.
b: On iPhoto 11 and later: Select one of the affected photos in the iPhoto Window and go File -> Reveal in Finder -> Original. A Finder window will pop open with the file already selected.