Select the first header container by clicking on it. Make sure that you see the word 'Container' to the upper left of the box. This will ensure that you have clicked on the correct element. Then click on the 'Inspector' tab in the sidebar. You are presented with a number of options. Here you want to select the 'Background' drop down menu and click on 'Color'.

Go back to the first header of your project. When you hover over the header container you will see that inside there is another element called 'Heading'. Click on that to activate it. You will know that it is activated when you see the word 'Heading' in the upper right hand corner. Next, click on the 'Inspector' tab in the sidebar. Here again you are presented with a number of options. Select the 'Text Style'  drop down.

Click on the header to activate the associated container. You will know that it is activated when you see the word 'Heading' in the upper left corner. Then double click to open the text tool bar. Make the changes to the text and then click anywhere outside of the heading element. Now again activate the heading element. Once activated click on the 'H' icon to apply your headline changes to the entire project.

To change the footer text and link hover over the footer container and click inside of the element. This will activate it. You will know that it is activated when you see the word 'Link' in the upper left corner. At times you may see the word 'Locked' instead. This simply means that the footer has not been linked to a URL, but the container is still the same one. Once it is activated follow the same steps as with the header. Double click to open the text tool bar, make your changes, click outside, and then again re-activate the element. Next, click on the container icon (the small rectangle) to apply the changes.

Here is a tutorial on 'Modifying an Existing URL in the Footer' - click here.