There are hundreds of different ways to facilitate journal workshops, below is just one of them. Teaching a journal workshop is easier than you might think. I have had great success with this type of journaling workshop.
Some convenient places to hold a workshop are bookstores, libraries, public or private schools, churches, community centers and even your own home. You can also rent a room at a local restaurant.
Determine the number of participants you would be comfortable working with in a workshop. Ten is an ideal number; twenty is pushing the comfort zone.
Decide if you want to charge participants a fee to attend the journaling workshop. Sometimes I charge a fee, sometimes I just ask for donations. It depends on the economic status of your participants.
Choose a theme for each class and gently keep them on that path. I generally choose themes that beginning writers are comfortable with such as: making lists of favorites and firsts, freewriting, writing about dreams and using writing prompts. Provide participants with a direction.
Not everyone will be comfortable sharing but one or two always will and you can lead the remaining discussion from there. Have participants share what they have written in their journal if they want.
Use examples from famous diarists like Anais Nin or Walt Whitman. Discuss the theme at the beginning of the workshop and then assign an in-class writing assignment.
Advertise your workshop on craigslist and in your local newspaper. Offer venues a chance to attend the journaling workshop for free if they allow you to host the class with their organization.
A few gentle reminders: Never force participants to share what they have written and never show anyone out of the class what a participant has written.
Be sure to check out http://www.double-roads.com for more great tips on journaling and memoir writing.