Hello. My name is***** can help you with your question.
To complete the transfer of the file save, you must locate the minecraft saves folder and then copy the file back to it.
Start by finding your saves folder. You can find all Minecraft folders, including the saves folder, by going in to the game launcher:
When you open Minecraft, it should automatically read the save file once it is there.
Is the the "worlds" folder that you moved? Where exactly did you put it on the new computer?
Ok... I can't tell by that if you moved from and to the correct places.
On the Mac, it has to be the file from ~/Library/Application Support/minecraft
And on the PC, the only way to put it into the right folder is to open the folder by going to file explorer, then typing
Don't miss the . before minecraft. If you can't tell me precisely where you put it, I can't tell you if you put it in the correct place.
If you are running Windows 7 or later, you can create a symbolic link right to the dropbox files, as long as you have dropbox instelled on your computer (so that it looks like a hard drive when you look at your computer files). You have to do this as an administator.
mklink /d "%AppData%\.minecraft" "%HomeDrive%%HomePath%\Dropbox\Minecraft"
That will create a link that the system sees as %AppData%\.minecraft, even though the files are in a different location. I know this is a little out there... but I'm trying to consider every possibility.