UNIX for Advanced & Expert Users

Hi,

what i need to do is build my own scheduler program.
I am supposed to display my own prompt. at this prompt i accept a command in the following format.

ls -l start 0:0:10:10 period 10 end 0:0:0:10

now this command should be executed in the background starting at 10 mins and 10 secs and should repeat and fork another ls -l after every 10 seconds since the period is of 10 secs. every ls -l should complete in the end time 10 secs or should be killed. ALL this is to be done in the background.

so my question is how do I start a process in the background from another process and keep it continuing till i end time expires. I also want to return to the foreground immediately after execution of each command. as in

1) $ ls -l start ... (i hit enter and command is thrown in background and keeps executing )
2) $ ps -ef (i am back to the prompt again and ready to accept a new command)

Might be a good idea that u do ur school assignments on ur own.

Nice homework