Hi,
I'm trying to make a website more accessible to people with intellectual disabilities. I was thinking about putting very simple and easily recognized buttons on the webpages which play mp3's (without opening a separate window, and the mp3's should only start playing once you press a "play" button).

I only know HTML and CSS so far, but as far as I can see, a flash audio button might do just the thing I'm looking for. I'm either looking for a single stand-alone button which reads out an mp3 file of an easy-to-understand version of the webpage, or 3 buttons (play, stop, rewind).

I'm using Mac OSX and don't have a Windows emulator.

I came across this website which seems to offer just the thing I'm looking for: http://www.sonicmemo.com/

I was wondering if something like this could be done for free, without the need for software, and if so - how?? I was also wondering how accessible/usable this option would be.

Any help would be greatly appreciated

ehmmm I will overlook comment about emulator as all what you need is internet browser (FireFox, Safari, Netscape Navigator, IE)and some text editing tool in case you do not have dremweaver or similar
As you have minimal knowledge of web technologies I will recommend you to look at this tutorials on w3schools.com or if you know flash you may do it as the guy did (in flash create button,add on_click event and play mp3)

As far as accessibility goes, most people should have flash player now (since it is a free download), but people with slow internet connections or who are not computer savvy might be hesitant about downloading and installing something online they are not too sure about.

You also need a server that supports and permits serving streamed music.