networking problem in virtual machine

Hi, I am running scientific linux guest on ubuntu host.

The problem is that the guest machine doesn't have any ip except from the loopback.

I want that the guest OS will be in the same local network of the host and not part of internal network that virtualbox create.
In other words I want other computers in the same local network of the host to be able to connect the guest OS as if anther computer was added to the network.

How can I do that?

I tried bridge but for some reason it doesn't work for me.

well I solved it.

It was a problem in the ifcfg-eth0 file and not in the virtual machine setting.

If anyone has this problem then you can look in the following link:
Setting Up a CentOS / Red Hat Linux DHCP Client