Here you can write procedure, create(and drop) database, create tables, create schema, privilege etc.
To create a table on your database. it is a matter select your database on the left side. then under the schema, which should be public, unless you created other schema. Then under it is a set of many thing, that I am unsure of.
You can create a table by right click on tables, and click new tables
And it shows a table editor. Which make life easier for gui oriented user.
To install pgadmin 3 on ubuntu.
apt-get install pgadmin3