Cisco 2950 with 2 Vlans

I am not a Cisco Guru but I can hold my own. I have a 12 port Cisco 2950. I am wanting to put 2 vlans on this switch. I have 2 subnets both are 255.255.255.248. 1 of those subnets does not have any IP’s left and cannot have more added for various reasons. I have the 2 vlans configured with certain ports in both and I would like port 12 to be the connection between the switch and the router which is a Cisco 1720. I want both Vlans to go through that port. Can anyone tell me if this is possible and if it is can anyone give me any ideas?
Thanks.