The blue box that contains the form components has a background image and a border applied to it. You can change these properties by doing the following:
First select the box. It is named “Lead Gen Area”. It is easy to see what you have selected if you open the left hand panel that show the page contents. To open the panel click on the small white arrow in the vertical black bar that is along the left edge of the editor.
Once you have the “Lead Gen Area” box selected, look to the properties panel in the right. Under “Background Properties” section click the remove button. This will remove the background image.
Above this is the “Border Properties” section. Select “None” from the drop down menu label Border if you would like to remove the border.
If you would like to change the color of the box, click on the color swatch under “Background Properties” and pick a new color.
I hope this helps you achieve what you have in mind.