You can learn more about Checklists here. In this post I just want to cover how you would go about attaching a Checklist to multiple contacts in bulk.
From your Advanced Search page, after running a search that will include your desired contacts, place checks to the left of the names of those contacts to whom you want to attach your Checklist:
In the example above, I've run a search that yielded 99 records (only partial results are displayed in the screenshot) — I then selected six of those records to whom I want to attach the Checklist.
My next step would be to click Options in the Result Options widget to the right of my search results and then to select Bulk Checklist Assignment from that menu:
After clicking Bulk Checklist Assignment, I'll then see the Attach New Checklist dialog, where I can add then choose from my existing Checklists to attach one of them to these six contact records:
The Checklists available here are those that your database users have established within your CRM - you can learn more about adding Checklists to your database here.
To select a Checklist, just click the arrows in the Available Checklists box, click your desired Checklist, choose a Start Date and then click Attach Checklist:
In the above example, once I click Attach Checklist, these six contacts will have the "A Clients - Monthly calls" Checklist attached to their records, with Checklist tasks for each of them showing up in the Reminders section of your Dashboard on the applicable date.
As you can probably see, it's a quick and easy method to set up reminders for a predefined set of tasks to multiple clients at one time.