New to Oracle, usually work with SQL Server.
Is there an easy way to backup an Oracle database from SQL Developer.
No. And then yes. Well, it depends.
What are your requirements?
Do you want a backup of the database ...
Then RMAN is your tool of choice. Yes, RMAN is pretty complex and has a steep learning curve. However, once you have mastered it, you will benefit from a large variety of possibilities that RMAN provides you with, e.g. central RMAN catalog for multiple Oracle instances.
Do you want a dump of a database ....
...then you might want to consider using the EXPDP (see: Data Pump Export) and IMPDP (see: Data Pump Import). These tools provide you with the ability to obtain schema-specific data and import the data into different tablespaces; or to filter the export via table names, dependencies. On import the schema can then be re-linked to a different schema (see: REMAP_SCHEMA), etc.
SQL Developer has the capability to export data using a wizard. This is similar to the built-in EXPDP and IMPDP tools provided with the RDBMS installation. A quick guide to using the wizard can be found at: Exporting and Importing Metadata and Data and there in the section Using SQL Developer for Exporting and Importing (Tools | Database Export).