Pond5 is a good place for you to get what you want!

To make good money in such a short period of time you would have to get some freelance work. To get freelance work you need an online reel, whether it is a website, a YouTube channel, Vimeo account, etc. if you can't show your skills you won't get hired. Also, you are only 16 and even if you can work legally the people that could potentially hire you may be reluctant to do so because you are a minor.

One way you can make money with your After Effects skills is by creating templates in which you can easily replace images and text and selling those templates on websites like pond5.com, envato.com or 100wa.com/en/
How much you will make depends on how good your templates are, if there's demand for them. The more templates you upload the more chances you have to make some extra cash. Make sure they are good!

100wa.com/en/ Would not recommend at all.

turkeyFx, why?