Route packets over specified interface

Hi,

I'm quite new to unix networking and ip tables. I'm running a debian (htpc) server with two NIC's; eth0 and wlan0.

I'm trying to set it up in a way that eth0 is the default interface for internet, but some processes should run through wlan0.

For example, I'm using eth0 for downloads and other bandwidth intensive processes but I want things like Spotify to run through wlan0.
For Spotify, this should be a rule in iptables:

What's the best way to approach this?

Thanks

For starters, whether IP ranges are "open" has little to do with whether your computer actually uses them.

You need to set up rules in your routing table, not your firewall, that things going to IP's related to spotify should go to gateway x via interface y. This rule has to come before your catchall rule.

I know, I was just quoting something telling me which ports and ip addresses they use. I just need to point to this port or these addresses with the wlan0 interface if I'm correct