Let me compliment you on deciding to be a trainer. I am taking the liberty of adding my suggestions for your consideration.
To be a good trainer a prerequisite is good communication skills, and in particular effective presentation and public speaking skills. However, the heart and brains of the training still remains the domain knowledge but even the most knowledgeable person would fail miserably as a trainer without effective communications skills. To further improve your communication skills find a local Toastmasters club in your city and join them.
To get the academic inputs on training you can do the course from Indian Society for Training and Development (ISTD). Alternatively you can also attend Train The Trainer (TTT) programs offered by private institutions.
Ideally some work experience would have helped you gain valuable insights that you could utilize in your training content. To make up for the lack of experience, focus on reading more about the areas / topics in which you hope to take the training. Proactively seek out situations, examples, case studies that suit the contents of the training programs you design. Engaging the participants whilst enhancing their knowledge should be the underlying principle in developing your training program. Enabling participants to quickly assimilate the learning and throwing up realistic possibilities in implementing the training in their work environment should be the mantra that you chant when delivering the program.
To get going, focus on those topics that you are familiar with, confident about, passionate about or have a good grounding in. Keep updating yourself by reading extensively and start outlining the broad course contents keeping in mind the type of audience you are likely to address. In particular pay attention to the type of exercise, examples, activities that you will use during the program to reinforce a point or make the learning relevant. I would also suggest that you attend some corporate training by professionals on topics of your interest to get a feel of how it is structured and delivered.
If you have no corporate training experience, ideally take a few sessions for post graduate students in colleges or for social service clubs like Lions and Rotary's so that you gain in experience and also can fine tune your material. Once you are confident, approach a few corporates and the first few training programs are vital for future reference and for your own confidence.
I would also invite you to visit the following Inspirational and Motivational Blogs which can also assist you in improving your vocabulary and communication skills.