There are two ways to upload files to Google Docs:
1. Dragging files directly into your Documents List or collection
One big advantage of dragging and dropping is that you can drop directly onto collections and sub-collections. When using the upload button, on the other hand, you will upload to your documents list and can then drag and drop onto collections and sub-collections. This feature is available only in the latest versions of Chrome and Firefox. If you aren’t working in the latest version of Chrome or Firefox, you can click the Upload button and select Files... from the drop-down menu.
2. Clicking the Upload button and selecting Files
To manually select files from your computer to upload to Google Docs, follow these steps:
In your Documents List, click the Upload button and select Files... from the drop-down menu.
Select the file you'd like to upload to Google Docs. To select multiple files, press Shift or Ctrl and click all the files to upload.
When you upload a file, a box that indicates the progress of the upload appears in the bottom right of your screen. You can minimize the box, move it to the left or right of the screen, or share directly from the box by clicking the Share link. When you’re done, you can click the document title to open the uploaded file or close the box by clicking the x in the upper right of the box.
Important! Once the file has uploaded to your documents home, drag and drop it to the collection you want it to reside in.