If you have access to YouTube, you can watch the video at THIS LINK
The information in this video will assist you in creating a floor plan. Although the goal is to create a 3D model of the house you have chosen, following the instructions in this video will set you up for success.
Introduction to drawing tools in SketchUp
How and why to create groups
How and why to create components
Tip for success:
Do not watch the whole video and attempt to learn all of the information in one go. Watch each chapter and copy what the instructor does in your own model.