To enable routing you need to make a command
echo 1 > /proc/sys/net/ipv4/ip_forward
But with your configuration you also need a NAT. Because addresses 192.168.*** will not be routed to Internet, it is for private local networks. For enabling NAT, you need to add iptables rule:
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
And FORWARD ACCEPT rules in filter table if you use it. By default, I think, all is accepted - you should change this if you have other connected clients you want to not be routed. These commands need to be executed after every boot, so write them on starting script, for example /etc/rc.local.