To start with, I need to make some assumptions, as the information you have given is not very much. The ISP will provide an ethernet connection for you, and your PC will use DHCP to get it's own IP address.
Based on that, you should be able to use the following.
First erase any existing configuration on the router. At the # prompt type
wr erase
Accept any questions by hitting the return key. Then power off the router for ten seconds, and turn it back on again. When it asks if you want to do the initial config, answer no.
Type the following
en
conf t
enable secret {password for enable mode}
no ip domain-lookup
ip classless
ip dhcp pool LAN
network 192.168.0.0 255.255.255.0
default-router 192.168.0.1
dns-server 208.67.222.222 208.67.220.220 (or replace with the DNS servers supplied by the ISP)
!
interface fastethernet0/0
description ** LAN **
ip address 192.168.0.1 255.255.255.0
ip nat inside
no shutdown
!
interface fastethernet0/1
description ** Internet **
ip address dhcp
ip nat outside
no shutdown
!
ip nat inside source list 1 interface FastEthernet0/1 overload
!
ip route 0.0.0.0 0.0.0.0 FastEthernet0/1
!
access-list 1 permit 192.168.0.0 0.0.0.255
!
line vty 0 4
access-class 1 in
password {telnet password}
login
!
end
wr
That should get the basics going. If you have a fixed IP address from the ISP, put that in the FastEthernet0/1 config, instead of the dhcp part of the command, and also change the ip route to be the ISP router, instead of the FastEthernet0/1.
You may not need the "ip route 0.0.0.0 0.0.0.0 FastEthernet0/1" command at all, as the default route should be inserted by dhcp from the ISP. If on a newer version of IOS (mostly I still work with 12.2) there is an "ip route 0.0.0.0 0.0.0 dhcp" command that you could also use to replace this. Try each one, and do a 'show ip route' command to see if the default route has been put in the table. When it has, stop !
Provide some feedback here if you are having problems, or need more information. A copy of the configuration (show config command at the enable prompt # ) will help a lot.
I apologise if I have left anything out, (I am sure someone will point this out !), but I did this from memory.
Consider you have link which is terminate in ethernet port of router and use internet in your LAN. ISP provide you LAN and WAN ip pool. So to configure steps on your router -
configure line console, aux, vty, enable, enable secret password.
configure interface fa0/0-
router#conf t
router<conf>#int fa0/0
router<config int># ip address <ip address>
router<config int># description WAN
router<config int># ip nat outside
router<config int># no shut
configure interface fa0/1
router#conf t
router<conf>#int fa0/1
router<config int># ip address <ip address>
router<config int># description LAN
router<config int># ip nat inside
router<config int># no shut
configure default route -
router<conf>#ip route 0.0.0.0 0.0.0.0 <ip address of ISP/Next hop ip add>
configure ACL and PAT -
router<conf>#access-list 1 permit any
router<conf>#ip nat inside source list 1 interface fa0/0 overload
Save configuration in startup-config file -
router#copy running-config startup-config
then check configuraiton by -
router#sh run
router#sh start
check port status –
router#sh ip int brief
check ping to each port and ISP ip address.