Where is the command line?

I'm trying to learn postgreSQL. I installed 9.3.1. on a PC running Windows 8. I needed that version to work with some DHI software. It installed successfully. I now have a number of postgreSQL associated items in my list of apps. They are:
Application Stack Builder

installation notes

pgadmin documentation

pgadmin III

postgreSQL documentation

postgreSQL release notes

Reload Configuration

SQL Shell (psql)

That's The problem is that it doesn’t tell me where to iuse that command. I have no program called “postgreSQL on my computer despite successfully installing the software. The only program that has a command prompt is the SQL shell one, and that doesn’t seem to be right, because none of the things the tutorials say comes next actually happens.

I used the pgadmin III to create a new database and new user in order to log into the DHI software. That's as far as I know what to do with the DHI software. I'm trying to learn what else to do with the postgreSQL, so I've looked up a bunch of tutorials. They all start out

To create a new database, in this example named mydb, use the following command:

$ createdb mydb

That's The problem is that it doesn’t tell me where to use that command. I have no program called “postgreSQL” on my computer despite successfully installing the software. The only program that has a command prompt is the SQL shell one, and that doesn’t seem to be right, because none of the things the tutorials say comes next actually happens.

I looked all over pgadmin and could not find a command line, though it does have menu items for creating a new database. This leads me to suspect that perhaps I have a different sort of interface. However, I can’t progress in the tutorials because I can’t find a command line anywhere, and I can’t find any tutorials that tell me how to use interface I have, if that’s what the situation is. Any advice?

Michael