Nish....
If you are interested in Security then I'll suggest to start with CompTIA Security +. This one is considered as the starting point to get into security field. Once you are done with this then you have many options open to you depending on your specific interest.
For Networking, CCNA/MCP is your starting point and then later on you can proceed to various fileds like Designing, Security or Administration of networks......again that depends on your interest.
I'll suggest you to go through various job sites and have an idea whats there in demand in your local job market and then plan and go ahead with your choice. You are already done your Engineering in IT, compliment it with some certifications and you can make a good money for you.
Hope this helps
