Newbie help

We do have a website that was made before I took over.  I don't really
know too much about search engines.  I am fairly confident in our
metatags, but I wonder what else can be done to help our search engine
results.  I wonder about search engine submisions.  Is this something
that needs to be done repeatedly?  I suspect at one time we submitted
to yahoo, google etc.  If I resubmit, how do I do that?  Please
remember, I am a novice.

Thanks,

Peter