Even if there were online opera lessons you had to pay for, I doubt very much it would get you far if you actually hope to sing professionally someday. Meanwhile, please bother your busy school choir teacher. Even if he can't give you some basic voice lessons to get you started, he would be the perfect person to ask if he knows any local voice teachers that can train you properly at a reasonable cost.

Please stop trying to train yourself. You can seriously injure your voice. Especially if at 16, if you decide the best way to learn is to try to copy the sound from a professional adult opera singers who have spent longer than you lived so far, just training to be able to sing the way they do.

It's not just a matter of sounding big–you actually have to have a voice of a reasonable size naturally. At 16, your voice isn't even fully developed. You can expect to learn some basic classical repertoire like a few simple arias, art songs, etc, but you must have a teacher to guide you and train you as the 16 year old you are–not what you might sound like at 30.

Furthermore, some amateur singers when they think "opera" think "high notes". They may attempt to sing higher and higher without stopping to consider that their own voices may lie lower–and that's okay. Many famous operatic roles are written for baritones and basses (quite a few of Mozart's for example).

Since good voice teachers make their living giving lessons (or even selling voice training programs), I would wonder why anyone would be willing to do "free interactive lessons" online to anyone and everyone asks. Imagine the amount of time that would be involved in training just one student!

Another thing you might check into, depending on where you live, is a local opera company. Many professional companies actually have youth programs to introduce singing and opera at age appropriate levels for children and teens.

For example:
Http://www.kcopera.org/education_outreac…
Http://www.nycopera.com/aboutus/stafforc…
Http://floperatheatre.org/florida-opera-…
Http://www.santafeopera.org/communityact…

Check into it. Some of these programs are free, but even in case where tuition is charged, there are often things like scholarships and financial aid for kids with talent but little money.

Once again, your choir teacher probably knows what programs may or may not be available in your area. Just ask. And stop training yourself before you get hurt!

Some people give free lessons on youtube.

Http://www.youtube.com/results?search_qu…

Well singing lessons usually go for about $20 a 30 min lesson and most people take them once a week. But if youre really low on cash maybe you could take them less often. Or find a kid who is studying voice in college to give you cheaper lessons.

Also, a lot of places(music stores) that have teachers will let you try out one lesson for free before deciding if you want that teacher or not. Try out as many teachers as possible to find who you connect with the best. While still capitalizing on some free lessons.