Google Drive can be organized in folders, very much like a computer hard drive. You can upload all types of files to Drive - PDFs, image files, video files, and more! You will be able to generate a preview of most files types within the Google Drive window, but will have to download files that are not made with Google Apps (Sheets, Slides, and Docs).
The files you upload or create will appear in My Drive.
Files other share with you will appear in Shared with Me.
To create new files or upload files from your computer, click the New button and select the appropriate option.