Can't upload Image to server

I’m making a simple PHP application which can upload an image to server.

I’m using Digital Ocean. They are great especially the support team.

I uploaded via FileZilla, my folder’s name " PHPFileUpload", in this folder contain a sub folder uploads to contain image which could be uploaded, file index.html to show the button select image to upload and file upload.php.

I did it in my localhost, everthing work well, but when I did it in real server. I mean Digital Ocean, it didn’t work.

I spent for one day to solve it, but I still can’t.

Please help me to fix it. Thank all Sorry about my english, it is not native