I've been reading the different guides, and frankly I can't seem to find the right one I should be reading.

Here is really what I want to do.
I want to redirect everything that starts with:
www.abc.com/wp-content/uploads/2011/02/xyz.jpg
(example: www.abc.com/wp-content/uploads/2011/02/xyz.jpg%22%20blah but www.abc.com/wp-content/uploads/2011/02/xyz.jpg should not be affected by the rewrite)

to:
www.abc.com/tag/def/

"/wp-content/uploads/2011/02/" is an actual folder, but "/tag/def/" does not exist as a physical folder.
Also, please note that the intentionally badly written URL of the example contains %22 (a space) and %20 (a quotation mark), something I'm not sure will need the escape '\'

Also, I'm not sure where to upload the .htaccess file since the target result is not an actual folder. Should I upload it in "/"? Or under "wp-content/uploads/2011/02/"?

Thank you!