To get an existing script uploaded...

First, log in, then on the Dashboard page click on the yellow New Script button:

When you click on that button, the Create New Script popup box will show up, where you need to enter some details about your script (the title & genre, optional logline and descriptive tags, etc.)...

To specify the script to upload, either click in the dashed Script File box to select the script from your computer, or just drag and drop it there. Remember, it must be an FDX, PDF or TVE file.

When you have chosen the script file and have entered the other needed information about the script, scroll to the bottom of the popup box and click on the Create Script button:

Your script will be uploaded and converted to be fully editable (this may take a few seconds to complete), then you will be shown the script information page for your new script, ready add collateral material, edit the script or even invite others to collaborate with you:

When you return to the Dashboard

You will find the script in your Screenplays listing: