Hi Sri Ram,
Welcome to SCN. Before getting into answering your question, let me say a few things.
When posting in a Professional Forum, please keep in mind certain things:
1. Be very specific with the question you want to ask.
I say this because the title and subject of your question mean two different things.
2. Do a little bit of research on your own before posting in the forum.
Most of the information you need is already available on SCN or internet. Asking the same kind of questions just increases the noise in the forum, making it harder to search for relevant information.
Coming to your question(s):
How to learn SAP FI/CO online?
Search online for Online training institutes and register with them after cross-checking their credentials in the market. The rest will be taken care by them.
Can I learn FICO online?
Sure, why not?
Could you suggest me with this about the opportunities with SAP ABAP AND FICO?
Yes there are enough opportunities in FICO and ABAP. What exactly is your interest? ABAP or FICO? Btw, both can be a handful if that is what you are thinking.
But learning fico online would help me out getting a job or should i learn in an institute?
Whether you learn FICO online or in-class or self-learning or from a SAP Education Partner, it does not automatically entitle you for a job. Getting a job is directly dependent on the amount of efforts you put-in and the confidence you show in interviews.