Use the schedule capability. Run through what you want to backup, and schedule it. Then look in Task Scheduler in control panel - the ntbackup scheduler routine should create a scheduled task that which contains a command line that would run the backup. Simply copy the command line to a batch file and create a shortcut to the batch file.
It may be more than you're asking for, but I have a backup script on my web site you're welcome to use -
www.lwcomputing.com/mysoftware.asp