You can draw a line using one of the options as shown below.
Then mark 1st point i.e. 'Start Point' and then another one 'End Point'.
In above figure 'P1' is the start point and 'P2' is the end point. Once you have given two points a line will be made as shown above.
Select Line tool from Insert menu or from Entity toolbar.
Mark the first point(P1).
After Marking 1st point you will get a infinite line along this mark the 2nd point (P2).
Line N Points : This is another and good option to draw a line. If Template edge is rough then its possible to create error in drawn line relative to that edge. To avoid this error use ' Line N Points'. To select this choose 'Insert Menu > Line N Points' and start marking from one end to other end, also use zoom window for more accuracy while marking. After you have entered sufficient number of points, you can click right mouse button. This will be the last input point.
Figure shows line with multi points. A approximate line which may or may not pass through all these points will be drawn.
Select 'Line N Points' tool from Insert menu or from Entity toolbar.
Mark the first point
After Marking 1st point, start no. of point to marks with reference to that you want to draw a line. Marking Pn point press right button of mouse to end that and you will get desired line.