The best reference for DBMS_JOB is the documentation (available many places online including tahiti.oracle.com). The basic syntax for submitting a job is:
dbms_job.submit(job_number, what, next, interval);
Here is a sample block:
declare
v_job number;
begin
dbms_job.submit(v_job, 'procname;', trunc(sysdate + 1) + 2/24, 'trunc(sysdate + 1) + 2/24');
commit;
end;
This would run a procedure named procname at 2:00am every day. Note the required semicolon after the procedure name and that the interval parameter is submitted as a string.
There are some init.ora server settings (job_queue_processes, etc.) required - please refer to the documentation for the specifics.