how and where to audition for a movie/tv show/ commercial etc.?

That's not how the industry works. Professional acting is a business and companies are in it to make money. It's not cost effective or efficient to hold open auditions where anyone who wants to be in a movie can show up. For most professional roles you have to be invited to audition, usually through a talent agent.

Here's how it works. A casting director is hired to help cast a show, commercial, movie etc. If the casting director is already familiar with an actor who they think would be good for a role, they'll contact the agent for that actor (or contact the actor directly). The casting director will probably also write a "breakdown" - a description of the project and the roles to be cast. The casting director then releases the breakdown through an online communication network. They decide who receives the breakdown. They may release it just to talent agents in LA (or NY) or they may release it to talent agents nationwide.

Talent agents review the breakdowns and submit their clients for the appropriate roles. (Submit means they send in the actors head shot, acting resume and acting reel showing the actor's previous screen work.) If the casting director is interested, they contact the agent to set up an audition for the actor.

So if you know the casting director for a production you can try to "self submit" which means you send in your professional head shot, acting resume, and acting reel directly to the talent agent without representation. But since you don't live in LA (where most of the auditions occur) you probably have a better chance of winning the lottery than getting invited to audition.

And you can't just hire an agent. Agents are paid on commission, getting a percentage of what their clients make. Since they are paid only if their clients book jobs, they're picky about who they take on as clients. So they are looking for clients who are "marketable".

And it isn't enough to be "noticed". Actors are not just "discovered". It's like starting a company and you are the product that has to be marketed and sold. So you need a good product (talent, training and experience) but you also have to understand the business end of things.

So the only way a minor can have a professional acting career is if THEIR PARENTS are very actively involved. Your parents will need to be willing to be the CEO of any acting career you attempt. They will have to do the research and learn the industry to protect you from scams/rip offs and make good business decisions for your career. The bizparentz.org website has helpful information for them.

Good luck.

Your parents need to Hire an Agent/write a Resume and Have Professional Photos taken

at 14 you cannot sign legal agreements