First, I haven't used PHP with Oracle although I use Oracle extensively. There are a few articles out there on the subject. Check out:
Configuring PHP with Oracle 8i Support 9i should work more or less the same way. I'm not sure about Oracle 10G support. You can google for more.
As for how to create tables with Oracle, etc., the database comes with SQL*Plus, iSQL*Plus, and optionally Oracle Enterprise Manager (OEM). SQL*Plus is a commandline interface for running queries, creating tables, adding users, etc. iSQL*Plus is the web version of that and requires Apache (which comes with a standard Oracle install these days.) OEM is a standalone java app that presents a gui interface for most of the admin functions like creating tables.
There are also third party applications you can use like TOAD, for example, that will give you a nice gui, if you prefer that over the commandline or OEM.
I wasn't sure from your post if you were installing Oracle from scratch, building a new database, or if an existing database already existed that you were building a schema in. If you have a database administrator to rely on, definitely go that route. Oracle is a lot more involved (sometimes unnecessarily so) than MySQL or many others. You can find complete documentation, etc. at
http://otn.oracle.com (you'll have to sign up for a free account to get to the documentation). One more thing: Oracle's architecture is different from MySQL, Postgresql, DB2, SQL Server, etc. In all of the other databases mentioned, you can have multiple databases within a single instance or set of server processes. Oracle has at most one database per instance. You can create multiple schemas/users within a database, each with their own set of tables, indexes, stored procs, etc.
Oracle offers a development license for free, but does expect fees for actual production use.
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