1) Go to http://timeline.knightlab.com/

2) Download the Google Spreadsheet Template that's on that website.

3) Use this US History Timeline to Drop dates, text and links to media (pictures) into the appropriate columns. Note: Don't change the column headers, don't remove any columns, and don't leave any blank rows in your spreadsheet.

4) Follow the rest of the directions on http://timeline.knightlab.com/ to turn your spreadsheet into an awesome online timeline, similar to this one here.