Internet connection failure

I have finished building a small home network. My DSL provider limits me to one static IP address. I give teh IP address of my DHCP server to the DSL provider. During testing I find that I cannot aceesss the internet from the workstations. I ping all the devices inside the DHCP server successfully. What is causing me the problem?
The following info about my system may be helpful
DHCP enabled
IP address : 192.168.10.23
Subnet mask : 255.255.255.0
Default gateway : 192.168.10.1