Need help with .htaccess rewrite rule

Hi webdeveloper friends,

I need help with rewrite rule as my website looks not SE friendly now. It is all dynamic URLs and I am unable to figure out how to rewrite it properly.

This is my website topnamebrands.net

The links for the brands look like:

http://www.topnamebrands.net/?filter=%3AGucci%3A

And the different categories like:

http://www.topnamebrands.net/?filter=%3AGucci%3ADresses

And if go deeper is:

http://www.topnamebrands.net/?product=_id_4766

What rule to apply to have something that look like:

topnamebrands.net/Gucci/
topnamebrands.net/Gucci/dresses/

this is just an example, it can look different, but similar.

Thank you for your help!

Kind regards

Kal