.htaccess modification since installing photoplog

[LBSources]

I feel like a n00b asking this question, but .htaccess is not something i'm familiar with ..

So originally i had installed menalto gallery and it was located @ http://www.mydomain.com/gallery

I today installed photoplog and its located at http://www.mydomain.com/forum/gallery

I'm using wordpress and thats whats at http://www.mydomain.com/

How can I manipulate my .htaccess file to reroute

http://www.mydomain.com/gallery -> http://www.mydomain.com/forum/gallery

current .htaccess looke like

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteBase /
RewriteRule . /index.php [L]
</IfModule>

# END WordPress