how to configure firewall in packet tracer??

well this scenario is part of what im doing, i used the access list but the will be connection between two routers and i want to secure the connection so that the network wont be hacked cuz if i use access list only even if it denys or accepts the ip address it can be hacked i mean intruders may be able to enter the network some how but if there was a firewall even if he managed to pass access list there will be this firewall to stop him. or what do you think?

i used the access list but the will be connection between two routers and i want to secure the connection

Why you need two routers here ?

if i use access list only even if it denys or accepts the ip address it can be hacked i mean intruders may be able to enter the network

No ip address will enter into the network unless router/firewall allows it. Firewall also will receive the IP and choose to deny/entry into the network depends on the policy, in your case router configured access list decide to choose whether it can allow the outside ip entry/deny into the network.

Mujix, It would be helpful to post a link of the .pkt file so that we can give better answers. You can upload here: www.2shared.com/

Regarding the matter, as far as I know, it is not very easy to get past an access list (if it was configured correctly, comprehensively, and the routers were patched with most recent IOS). But any how, a basic firewall will by default block all inbound (outside originating to inside) traffic and allow outbound (inside originating to outside) traffic. One easy way to do this is to implement NAT/PAT (which most PIXes and ASAs do). You could also use ACLs to do this. And you can off-course use both.