OpenVPN server routing problem

Hello, I'm setting up my own openVPN server

I generated everything for the certificates and I can create a tunnel between my server and my client. (I can see the nic 's in ifconfig)

But when I try to acces the internet or simply ping my server true the tunnel, I can't get a response. Even If I try to ping the client from the server true the tunnel.

I'm preaty sure it has something to have with iptable but I'm a noob with iptable so I would like to have some advices...