LinuxQuestions.org - Iptables please

ok. this is my first post here! i have done some research for iptables but i cant take it anymore! i need some rest from reading but i really need this to work! i have a linux pc being used a my router and as a server. i have iptables installed (may i add my cuzin did 99% of all the work on this router so to say i know everything would be a lie), apache, and some other stuff. now what im trying to do is open a port that will allow port 8602 to be open tcp and udp so a program i have called xbconnect (google it, the forum wont let me post the url because of spamming purposes) so that i can play online. please tell me the command. ive used this one but it doesnt seem to work:

Code:

iptables -t nat -A PREROUTING -i ppp0 -p tcp --dport 8602 -j DNAT --to-destination 192.168.2.2

and

Code:

iptables -t nat -A PREROUTING -i ppp0 -p udp --dport 8602 -j DNAT --to-destination 192.168.2.2

so what sould i do to get this thing to work. please help will be greatly thanked. i know there are many tutorials but i cant read another manual/tutorial right now however i need this to work as soon as possible.
need more info? just ask and ill tell you.