no network works with live cd but not when i boot from HDD

[Richieboy2001]

Me and My mate have been trying to install gentoo 'he has done it many times' and have encountered some problems. we can get a internet connection when we boot from the live cd we get an internet connection and we can ping things i.e. www.gentoo.org but when we finished with all that live cd noncense and got it to boot from hdd and installed the grub and what not then try and install KDE and it just wont work we cant even ping anything or even ifconfig comes up with some randome ip address 127.0.0.0 and has a subnet mask of 255.0.0.0 but i need an ip of 192.168.0.# we have tried manualy doing it but it dont work.
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Im Not a tramp, I just like living in a card bord box