Ok ive been using windows for a long time now, and I just installed Mandrake 10.1 community from some disks I bought. (when I bought them 3 disks came, and when I installed it asked for 5, im not sure if that has anything to do with my problem). so anyways, on windows I am always able to just automatically detect my lan and internet connections, and it does it automatically, but when I installed Mandrake and tried to access the internet it didnt work, I went to the mandrake control panel and tried to set up a new internet connection, but im not sure how, im connected to a router that is conneted to the internet via a cable connection. If I select lan should I be able to just click next, or do I have to enter stuff somewhere cause nomatter what I try it does not seem to work. Please help me.

To check, is your router connected via an ethernet nic? - if so, is your nic shown as a device name under "Network & Internet" - "Manage connections"? - if so, you've got a choice of using DHCP from your router, or setting up "static" info - either way, you can use the "Manage connections" tab for your static ip info, or DHCP indication.

Umm im not sure x.x well I tried to set up an eth0 thing, but it doesent work, and whenever I turn on teh computer it says an error on eth0, but still lets me in.

You'll get that eth0 error on boot until the relevant information has been "assigned" either via DHCP or "staticly" - to ask again .. - is your router connected to your computer via a NIC ?? can you actually see an eth0 nic device name displayed under "manage connections" in the MCC? - if not, post the output of:

lspcidrake -v

and

lsmod

as root user from an xterm.

maybe you simply have forgotten to activate your ethernet-card. log into a console as root (type su, then enter password) and type ifup eth0 (if your card is detected as eth1 type ifup eth1 accordingly). it should detect the router ip then.
if nothing shows up, give us the following information:
in console as root, type ifconfig eth0. what does it say?
what does route -n give as result? and what does iptables -nvL say?
it is also good to post your /etc/sysconfig/network-scripts/ifcfg-eth0 file.

good luck.