Inviting people to Dropbox is simple.
Dropbox is, foremost, a way to back up your files online and synchronize them to your other computers and devices. After you install Dropbox and put files into the My Dropbox folder on your computer, those files will be backed up to the Dropbox server.
But you also have the option of sharing those files, or any others, with other people. You cannot, however, add files to someone’s Dropbox unless you’re sharing a folder with them. Either they have to invite you or you have to invite them. This is not a free-for-all. It’s by choice.
Inviting/Adding People to Your Dropbox folder
In order to invite people to your Dropbox, simply:
1. Create a new folder inside My Dropbox on your computer.
2. Give the folder a name. (Like your name and the name of the person you want to invite, eg. John-Jane)
3. Right-click on the folder and choose Dropbox/Share this folder
This will automatically open a window in your browser where you type in the person’s email address (and a message if you like.) Then click the blue button that says Share folder. Then you have to wait.
What happens next is the other person receives an email asking them to accept your invitation. If they say yes, but they don’t yet have Dropbox installed they’ll have to do that first. After that, they will also have a folder called, for instance, ‘John-Jane’ in their My Dropbox folder.
Whatever you put in the folder will show up on their computer and whatever they put in the folder will show up on your computer. Up to the maximum of space you have. You both start with 2GB free plus a 500MB bonus for them accepting your invitation. You only get a bonus if they’re setting up a Dropbox account for the first time.
You can invite more than one person to a Shared folder. And you can create as many Shared folders as you like. I use Shared folders as a way-station. When I get something new I move it out of there to make more space for something else.
Follow the step-by-step instructions at Dropbox: Inviting, Accessing & Sharing.