Adding "www" to image addresses?

Using the admin panel for Hot Image Slider we can set the path, then the filenames of each image, but when they show up on the webpage it's trying to find them at http://ourdomainname (no "www"). For some reason our network here in-house refuses to acknowledge anything without the "www" so I was hoping to alter the image paths to include it. Is there a way to make it so that when the code is inserted into the page, it includes that "www" in the image URLs? Thanks for any help.

In modules/mod_hot_image_slider/tmpl/default.php

everywhere you see

$mosConfig_live_site

replace it with

'your site base link' - including quotes!

Hmm...I see where to change this but when I use our base URL, it gripes about there being an unexpected colon (in the http://). If I leave that out and just use the www URL, I get different errors. I can get those and paste them in if it would help. I've tried it with and without the periods next to the quotes too, and still errors. I'm probably doing something really simple wrong - any ideas? Thanks for your help.

How you mean error joomla error pops out or image url is still bad?

If joomla error:

Open file in file editor, open find-replace dialog

replace it with

save, that's it.

Yep, that's what I did. I can't even see the page to tell whether the image URL is still bad, I just get a plain white page with a Joomla error. It's different depending on how I do the find/replace (with/without the http://, with/without the dots).

If I replace '.$mosConfig_live_site.' with '. www.ourdomain.com .' - it doesn't seem to like the http://, and gives me this error:
Parse error: syntax error, unexpected ':' in /home/content/c/o/a/coastccu/html/cms/modules/mod_hot_image_slider/tmpl/default.php on line 64

If I just do '. www.ourdomain.com .', the page does load but then these errors appear where the image slider should be (and the URLs are still broken images because there's no "www"):
Warning: Division by zero in /home/content/c/o/a/coastccu/html/cms/modules/mod_hot_image_slider/tmpl/default.php on line 64
Warning: Division by zero in /home/content/c/o/a/coastccu/html/cms/modules/mod_hot_image_slider/tmpl/default.php on line 85

I took a stab at removing the dots/periods before/after those strings (although I assume it wants those there), but then I get the blank page again with this error:
Parse error: syntax error, unexpected T_STRING in /home/content/c/o/a/coastccu/html/cms/modules/mod_hot_image_slider/tmpl/default.php on line 64

Any ideas how I might be doing this wrong?

Whoops, that first example I gave was supposed to have an http:// in the text. The forum converted to it without...probably obvious but thought I'd clarify.