I expect that when your database is created, and during install of Oracle you can choose to create a "starter" database that has a simple schema in it, you would be most comfortable using "Enterprise Manager" to create your tables, indexes etc.. It gives you a gui for the entire process, and you won't get hung up on syntax errors through trying to hand code the SQL.

Still, when you do use it, take the time to look at the sql it is generating for each operation. there's no substitute for SQL knowledge.