Oracle has many Development Tools: Forms, Reports, Java Developer, BI Developer, DW Developer, Portal Developer, Web Developer.
You can see the content of each course in the links provided which are based on Oracle 10g release. You can get the 9i release courses from the first link.
So, for self-studying, you have to:
1- Get Oracle Database 9i or 10g from Oracle Technology Network (OTN)( http://www.oracle.com/technology/software/index.html
). Oracle allows developers to download their software for educational and personal use. Registeration required.
2- Get some book(s) about Oracle SQL and go in it throughly.
3- Get some book(s) about Oracle PL/SQL (analogy of T-SQL in SQL Server) and finish it.
4- Now u can go for the Developer Suite, so download it from OTN.
5- Get some book(s) about Oracle Forms and go eating it