Dropbox: Some questions on its application...?

Hi, I took someone’s advice and downloaded Dropbox to send/share large MP3 files that I have.

Now that it’s on my computer, I’m not sure how to use it. The instructions are skimpy (and like a lot of tech manuals, written by someone who skips over the important things because they are a “given”, I suppose.)

I know that you drag what you want into the folder. That’s cumbersome because when I open the other folder to take the files out of there…the dropbox window shuts. Don’t know how to keep that open to do the dragging of files.

Secondly, once they are in there, who has access to my files? Everyone? Or just the people I want to share them with?

Third, after I’ve asked other people I want to share files with to download Dropbox…how do I let them know to find my files in there? Is there a password, a link? That’s also not explained.

I hope someone who has a way of writing concise and very, very clear instructions can help me to figure this out so I can get these files out to my friends.

Thanks in advance!

DR