For details on managing this feature look to the signs and flyers addon management page found here in the support wiki

Once this addon is enabled within the admin tool the client sees the following option within their client side admin tool:

Once you click that link you clients will see a page like this one:

Within that you'll see build sign and build flyer next to each live listing for that seller in the system. To build a sign click the build sign link and you'll see a form like this one:

Your client will fill in the details they want for that sign. The software prefills any information for a specific field from the listing selected to create the sign for. The client can edit any information directly there if they wish. When done they click the build sign button at the bottom of the form

To create a flyer the client simply clicks the build flyer button next to the listing they wish to create the flyer for. That will open a page like the following.

and just like for a sign they would correct/fill in the information they actually want in the flyer and click the build flyer button at the bottom of the form.