Hi Toni .. You should choose a subject you are super interested in and passionate about since you will be required to write quite a lot of content on the topic. It is helpful if you also have some knowledge in the subject but if not, something you won't mind doing a lot of research on.

This blog by Kyle will be helpful in clarifying what exactly a niche is: A Niche is A Group of People Looking for Stuff This training series by Laura is excellent for drilling down a great niche: Finding A Profitable Niche You Love-Niche Definition Video 1 of 6 Good luck, Shannon

Toni,
Selecting a niche should not be too difficult.
You must have some hobbies or interests that excite you, your go to activity when you are not working or in a class. Pick one that you are passionate about. Once you select your niche you can zoom in on a specific portion of the Niche.
With a niche picked you can work through the training and before you know it you will have launched your business.

For example I enjoy Photography and therefore I started a site to focus on it. I have been active here for approximately one month and am an affiliate for two places, have a site up and running, working on donations, and selling my images.

You can do it. If you want some help send me a message with your hobbies, likes, dislikes. I am sure you will lock in on something big!