No Internet Access my VirtualGuest NAT

Hallo, sorry my english ist not so good.

I installed two guests with NAT. My Proxmox Server has

"" DHCP""
vmbr0 Link encap:Ethernet HWaddr 50:46:5d:9e:20:ce
inet addr:my-externel-IP Bcast:192.168.50.255 Mask:255.255.255.0

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My Guest ifconfig "UBUNTU"

eth0 10.0.2.15 Bcast 10.02.2.255

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how can I connect to the Internet by visiting
I have KVM Guests

Thanks