Please generate SQL Script of tables from MS.SQL and check the compatibility with Oracle.
Using SQL Server's DDL generation is unlikely to work, it will be littered with T-SQL keywords and SQL Server-specific DDL options.
To address the original question, the Oracle documentation itself is pretty decent. Outside of that PL/SQL in a Nutshell is a good reference, but if you are up to speed with T-SQL
you should feel at home with PL/SQL pretty quickly.