Hello Vlan Sample Configuration,
What you should be able to do in this setup is create a 2nd VLAN on the 4108 and then connect a cable to any of the ports on the 2626.
From the CLI (it is the most powerful of all the management interfaces) you would type something like this:
4108(config)# vlan 2
4108(vlan-2)# untagged b1
4108(vlan-2)# tagged a1
You would connect the 2626 up to port B1, and port A1 would be the fibre link going to the 2650.
Then on the 2650:
2650(config)# vlan 2
2650(vlan-2)# untagged 1
2650(vlan-2)# tagged 50
PC A would go on port 1, and 50 would be your fibre port to the 4108.
That should do the trick, once you've verified it works, do a 'write mem' on each of the switches to save the configuration.
Don't forget to assign points to posts that have helped you.
Matt