There are also options to do things in other ways in PGAdmin that might suit you a bit better. Right click on your server (where it says PostgreSQL 9.1) and choose New -> Tablespace. Give it a name, set the owner to the postgres user via the drop down. Enter your directory on the Definition tab. You shouldn't need to set anything else. You'll see the SQL used to create it on the SQL tab and you can compare it to what is here.
Once you have the tablespace, right click on where it says Databases and choose New Database. Again give it a name. On the Definition page, pick an existing PT4 database as a Template (this will save later steps - you won't need to run the schema definition manually), pick the table space. That actually should be all you need to do.