Let me give you an example first. Birthday cakes come in various shapes. Generally speaking, the cake plane is round and square, which is a simple explanation of the concept of plane. Similarly, a room is like a cake. To draw a floor plan, first draw the shape of the room with a ruler, that is, the outline of the room. Second, just like cutting a cake, divide the scope of each room. Consideration should be given to drawing one or more corridors in each range. Step 3, draw the door, draw an arc in the direction where the door opens until it reaches an adjacent line. The fourth step is to draw squares, rectangles or other figures in each room, and mark the names of furniture and kitchen utensils such as beds and tables in these figures.
Finally, considering that you are a junior three student, this is not the most professional method. If you are interested in the design of "house", you can collect the leaflets of real estate developers for reference and study.