Paper and pencil represent the Euclidean plane, but imperfectly. The page is finite and the Euclidean plane is infinite. Drawn lines are like geometric lines in that they represent distances, but drawn lines must be finite because they exist on a finite page. Geometric lines extend to infinity in both directions. Geometric points are dimensionless; they have no length or width. Drawn points are not really mathematical points; they must have measurement in several directions or they cannot be seen. As long as these approximations are kept in mind, paper and pencils can be valuable geometric drawing tools.
The straightedge is an aid to drawing straight lines. In modern times, carefully spaced marks on the straight edge allow the device to be used as a measuring device. For the modern geometer, the straightedge is often supplemented with another drawing tool: the triangle -- a plastic triangle that has one right angle. These are convenient for drawing 90-degree angles, although this is not necessary. To draw a 90-degree angle to a given line, set the compass at each end of the line, with the width less than the length of the line segment. The places where the two circles cross mark the end points of a line that is 90 degrees to the given line. Connect the places where the circles cross with a straightedge.
The compass is a device with two legs. The legs are joined at one end. One leg ends in a point and the other leg has some sort of marking device, usually a pencil. If the pointed leg is set at a point A, and the compass is held where the legs join and rotated, the marking device draws a circle. The circle will have its center at point A. The radius of the circle will be the distance the compass legs are set apart.
Protractors are usually transparent semicircles that are used for measuring angles. If you place the center of the protractor at the vertex of an angle and the flat bottom of the protractor along one leg of the angle, the other leg of the angle will cut across the curved -- and marked -- part of the protractor. The scale where the leg cuts across the curved part of the protractor indicates the angle between the legs.