Re: ALTER TABLE and adding FK Constraints - Assistance Requested

First, I am relatively new to postgres, but have been using database (design not administering) for about 20 years (you would think that I could figure this out - lol).  At an rate, I am trying to create tables that have forgein keys via a script.  What happens is if the table that is referred to in the forgeing key does not exist, the table fails to create.  Undertandable.  So what I need to do is create all the tables and then go back and alter the tables by adding the forgein key constraint.  I got that.  But what I am looking for is the correct syntax to add the forgein key constrant.  I have tried "ALTER TABLE <name> CONSTRANT <constraint description>" and "ALTER TABLE <name> ADD CONSTRANT <constraint description>".  But both fail.
 
Yes I am being lazy.  I should go through the script and create the tables that are referenced first then the ones with the forgein key.  But I also need to know this in the even the schema changes in the future and more constratins are necessary.  I have looked at the ALTER TABLE syntax on postgres but it refers back to the CREATE TABLE function.
 
Michael