packet forwarding from wlan0 to eth0

[brightside]

hi..
Im new to linux...my aim is to forward packets from wlan0(wireless) to eth0(wired) and then distribute internet to clients through eth0...ive tried googling, but everywhere iptables commands are written and the changes in sysctl.conf file...that is fine...but im not able to understand what all configuration should be done in files ifcfg-eth0 and ifcfg-wlan0.....im confused about the gateway to be written in both the files and also regarding the MODE in ifcfg-wlan0.....can anyone please tell me the basics of these two configuration files...