You can use the VOCPhax graphical interface to easily create faxes from g3, postcript, image files and others. You can then send multipage faxes to one or more recipients (but be sure to see the section of setting up faxing with VOCP).
Once faxing is setup, you can use VOCPhax (/usr/local/vocp/bin/vocphax.pl) to create and send faxes. Launch the program. You may now use File->Open g3 from the menu to open g3 fax files or use File->Create to create faxes by converting existing files in other formats (png, ps, pdf, eps, tiff, jpeg, tga, xpm, gif and bmp are among the supported formats). When this is done, click the add to Queue button in the VOCPhax view window. You will notice that the VOCPhax main window now shows a preview of the out queue containing a thumbnail of your newly created fax.
Add as many pages as you wish to send in this manner. You may reorder the pages by dragging and dropping the thumbnails to their new positions.
When ready, select File->sendqueue. A dialog will allow you to enter the phone numbers you wish to send the faxes to. Enter a phone number in the text field and click add. If you've made a mistake, select the phone number and click the remove button. When you're satisfied, click send.
That's it, the faxes should be spooled and sent the next time faxrunq(d) gets around to it (when that is depends on your configuration).
You can check the outgoing fax queue with the faxq command and delete jobs with faxrm.