For this assignment you have to find data from the original source. Many of the Reports and Statistics sections of this guide cite data, but they may be using other organization's data, and not be the original source of the data. Below are some government agencies that are the sources of original data. You will note that there are several "on ramps" for some of these data sources.
I find the Tables view in Social Explorer most helpful. For more tables go to Guided Search on the Census website: https://factfinder.census.gov/faces/nav/jsf/pages/guided_search.xhtml. Download the data into an Excel sheet (which can be copied and pasted into Google Sheets).
When it comes time to create charts, you can do so in Excel and Google Sheets.
In Excel - get your data in a clean table format (get rid of the percentage column, etc., only the data you want to graph), and then click on Insert/Charts and choose your chart type. To relabel the axis, etc., go to Add Chart Element.
In Google Sheets, click on the chart icon on the far right hand side of the toolbar.