There are three different ways to add assets to your project.
Click on your project to select it to make the assets tab appear at the bottom of the portal.
Drag the file you want to import into the assets tab.
Select your project to make the assets tab appear.
Click the "Add File" button.
Navigate to your file and select it.
Click the drop down button under your project and select "Show Folder"
Alternatively, navigate to
Drag your files into the directory to import them.