I could write blogs on how to learn the many features involved in working with COBOL, but I thought it would be better to add links here as I come across really good tutorials that are already out there.
As a COBOL coder, you will need to be familiar with a Mainframe environment as well as the tools associated with this environment.
IBM Redbooks
In the modern world, you can look up almost any COBOL coding related topic online. The IBM Redbooks are a reliable source of information for COBOL coders. You can search on various topics such as CICS, JCL, ISPF, DB2, SQL, and many others.
Compuware
Compuware is a software company that focuses on Mainframe. A search of the products on their site will give you information on such useful COBOL coding tools as Xpediter and File-AID.
COBOL Compilers
GnuCOBOL is a free COBOL compiler that’s easy to download and use.
COBOL Interview Questions
MindMajix put together a list of common COBOL programmer interview questions.