Non-druids will need to visit each ring they want to be transported to and gather a leaf before they can be transported there. This is a one time visit, so you could make an evening of it and just visit all 5 rings in turn to collect your 5 leaves.
Once you have visited a ring and gathered a leaf, any druid (who has that port) can take you there any time you'd like from where ever the two of you happen to be. You are not required to be in a group with the druid, (anyone can use the portal once it is established) and you will never have to gather a leaf for that location again.
Druids who want to be able to "drive the bus" have just a little more work in store. They need to first visit each ring they would like to port folks to and gather a leaf. Next they will need to return to the Temple of Life in North Qeynos (don't know the location for Freeport), and speak to one of the priests there (she is outside, down the steps and on the right as you enter the courtyard).
Once you speak to her, she will offr the quest(s) and also offer to port you back to the ring(s) in order to complete the quest(s). If you are doing multiple rings you'll have to pick the one you want to start with and figure out how to reach the others on your own.
The best thing I have come up with is this; after speaking to the priest and gathering the 5 quests, have a druid friend with all the ports meet you at the first ring and as you complete each quest, they can port you to the next one on your list. Saves you all the run/boat time of traveling from ring to ring to complete.