I've resorted to posting my issue on here, after finding no answers to my issue on the MediaWiki site.
I get the following message when I want to upload images:
The upload directory (/home/.taggie/***/***/uploads) is not writable by the webserver.
Research showed that I have to chmod the permissions, which I did through FTP. They're set to 777 (everything checked) and still nothing.
I'm not sure if there are any webhost-specific things that I need to know or do for this, which is why I decided to bring this up in a DreamHost forum.
If anyone knows how to resolve this problem, or what I am doing wrong, any help is much appreciated!