There is no such thing as a stupid question. It's the replies saying you are stupid which are stupid.

As to your question, fear not.... Any file you upload from your PC or any other device is not held on your phone.
All files are uploaded to the 'Cloud' and in this case it is Dropbox.
Files in the cloud can be viewed on many different machines but viewing is all you would be doing.
To get the file on to your phone you would have to download the file from Dropbox to your phone.

There are many ways you can do this but I personally prefer using a File Manager such as 'Solid Explorer' which can be set up to show/download all files in your Dropbox account.

 

I too really enjoy Solid Explorer, its a great file manager. That in combination with Dropbox is a great solution for managing files.

 

I have used Solid Explorer and it is nice, but I prefer ES File Explorer. I find the integration with Dropbox, Skydrive, G Drive, et al to be very smooth and intuitive. Please don't take this as a knock against Solid, just a different opinion.

As for files downloading from dropbox, they won't download to your phone unless you go get them. You can view the file list just like they were on the device, but stay on the cloud until you retrieve them. On the PC side, if you install the Dropbox app, all the folders in your Dropbox will actually sync with the PC. This means that all the choosen folders actually download to the PC.

BigRedGonzo