Advanced editing “posts”

Hi, I am a newbie to CMS and WordPress, but have experience with web design in general.

I am hoping that someone here can understand what i require, and can point me in the correct place…

Ok, so i have got my WP running, i have a nice theme downloaded, and have added some test posts and comments.

The problem i have is this, in the ‘edit post’ screens, it allows me to point to the location of a .JPG file, which is then used in the page.
I want this to be a .SWF file instead though.

Unfortunatly, just entering the path to my .SWF in place of the .JPG doesnt work, because the code generated automatically puts the html tags for < IMG > in place, and i would ideally need to change this.
…This is where i come stuck.

When i view my post on the blog in IE, and i right-clock and View Source, i can see the syntax, and can see what i would need to change so that it references the .SWF instead, BUT, i have no idea where you get to these files to edit them.
Idealy i would download the Post files, edit them in a text editor, then re-upload them back.

For example, typically WordPress creates the blog page called something like [looking at the URL in IE]:

https://www.domain.com/myblog/?=p9

Is it posible to locate the file that is in the example above “?=p9”

I hope someone even knows what im talking about…

Thanks