Hi Sivaram,
First create a variant for program SAPLKO71. then go to SM36 and give the Job name to be executed in background then click on steps> under ABAP program> enter the program name and variant>save.
Then go to "start conditions"> Date/Time>Enter the start date and time>click on the period values right bottom of the screen>Other period> enter the interval -10 or 15 minutes>check>save>save
Now your background job released to be run for every 15 minutes.
Go to SM37 and check your job.
Please let me know if you need any further help.