If you would like to send a reminder to only one person, navigate to the document containing the pending task. Once there, you can scroll to the bottom, and on the left side of the screen click on the task.
A pop-up will appear with the task details. At the bottom you can see who the task is assigned to, and click "Remind" to the right of their name. Then click "Save".
A reminder will be sent to only that person with a link to the document for them to complete the task.
You can use the reports feature to send reminders to multiple people with pending signatures. Start by clicking "Reports" on the left side of your main binder view screen.
Select "Tasks - Pending" from the reports menu, and the select the binder(s) you want to view.
Once all the pending tasks are generated, you can click on the check boxes next to the task reminders you want to send or click the check box at the top of the list to send all task reminders for this page. If you have multiple pages of pending tasks, you will have to go to the next page and select all again to send those reminders. You can then click "Send Reminders" at the top of the list.