syntax errors at "line 1" when executing every command

Hi list,

I'm using the latest postgreSQL with the lastest postgis.
When executing every command I want to use, I get the following error
message:

postgis=# createdb;
ERROR: syntax error at or near "createdb"
LINE 1: createdb;
^

I can use psql to reach my database, but after that I'm finished.
Can't use any command. I thought this was a Vista (PATH) issue
so I turned to Windows XP, however, I encounter the exact
same issue. What am I doing wrong ??

Thx
Steven