with some engines you may want / need to re submit, google is not one of them, howvere it is a good idea to submit any new pages once to google.
Most engines are removing free URL submission in favour of pay to be listed schemes, its still possible to list free with yahoo if you have a yahoo account, but MSN is now pay only.
A good serach engine will re index rounghly ever 2 weeks - 4 weeks but should visit you index page weekly if not daily (depends how often you update it).
Check your web logs and look for "bots" if you can see google or others crawling through at least you'll know it working!
Hope this helps
LP
Lordpercy.com