Create a db for a project on a Windows PC from a portable postgreSQL on an external disk

[manuelcaeiro]

I downloaded PostgreSQLPortable_10.4.1.zip and unzipped it on my portable disk in a subdir named pgsql.
The psql opens and prompts okay.
How can I create a database for a project on a Windows machine in a directory, say, on disk D: somedir/somesubdir/someproject?
Shall I add the pgsql dir to the Windows Path on that PC?
Must I place the pgsql directory on the root of my portable disk as I had to for xampp?
(edited Jan 26, 2019)
I also saw your comment at SourceForge on the repository of the pgAdmin portable repository saying that you "use it extensively to control my PostgreSQL Portable instance - and it works great".
Can you please explain me how?

Thank you.

P.S: Almost all programmer/support tools I use are portable versions on a portable disk.
Even my Git install, for example, is a portable, and I managed to configure it to open the git-bash anywhere from the command line (on Windows I have to put it on the Path). And also my xampp, although I had to unzip it on the root of the disk to make it work.