URL masking with htaccess

[kindian]

I have a domain on my plesk and I want that domain to redirect to another hosting account.

Example

My domain: www.mydomain.com
Other host: www.otherhost.com/mydomainfolder

Whenever a user enters www.mydomain.com on the address bar he is redirected to www.otherhost.com/mydomainfolder

I did that with frame forwarding, no problems, but if you right click a picture, you'll see on the propertis something like:

www.otherhost.com/mydomainfolder/picture.jpg

How to make that show www.mydomain.com/picture.jpg

?