Hi Dean, as this issue isn't related to the learning labs you might have been better posting in the CCNA user group or somewhere similar. Regardless, the answer is quite simple. VTP doesn't know what access ports on the switch belong to a VLAN, but it does make sure that the VLANs themselves are created where they're needed.
For example, if you have 3 switches A, B and C and want a VLAN from Port 1 on A to Port 2 on C, without VTP you need to log into all 3 switches and type:
name PC LAN
and then on A and C configure your ports "switchport access vlan 20; switchport mode access". When you only have a few switches it's not such a big deal and so VTP doesn't seem very helpful. When you have 20 switches however and 100s of VLANs it becomes a little more complicated if you have to figure out exactly which switches you need to create the VLANs on for the connections that you need. This is where VTP really helps as you only need to create the VLAN once, then log into the switches where you're connecting the equipment to assign the access port. The path itself is taken care of automagically.