What should I use for sound effects?

Mixing is basically adding effects to your songs (compression, reverb, eq) to make it sound more refined and not mud each other up. This is so that it “sits in the mix”.

Some of the stuff of freesound are copyrighted :flushed:

Most of them are free to use. Did you read the instructions on the website? If you think they are copyrighted, take a glance at this:

I don’t think you’ll get a copyright strike from this website. Aside from the copyright, if you follow the licenses, you can still use them for free.