The usual place to install a site is in the root so: planetbubble.org so users will find the site directly if they type in the domain.
The other option would mean the users would have to type http://planetbubble.org/wordpress to see your site.
To install your site in the root:
Unpack the wordpress install-files to your pc.
Open the wordpress folder > you will see a lot of files
FTP / upload all files to the root of your site.
e.g. http-folder of your site
After installing your site make sure you do the following:
make regular back-ups of your site and of your database; [two different things! The database holds your content]
Make back-ups every time before you make changes. It only takes a minute and can save you a lot of time and heartache if things go wrong
Find a nice theme to give your site the looks you want
Create a ‘childtheme’ of this theme, before you make any changes.