To draw a straight line on the board, select Line from the toolbar on the left-hand side, then click on the board, a small line is added to the board as shown below:

Lines can be managed as follows:
- Drag any of the line's anchor points to change its length.
- Drag the anchor point to change the angle in which the line is drawn. You can also press Shift while dragging the anchor point to change the angle by 45 degrees.
- Click the circle icon to select the color and the width for the line, the following selector is displayed:

Drag the slider to the right to increase the width and click the color you want.
- Click the Lock icon to lock the line and prevent changing its location. The icon changes and you can click it again to unlock the line.
- Click the comment icon to add a comment. More information on comments is available in Comments.
- Click the three dots to select similar objects on the board, bring the selected object to front or send it to back, or remove the selected object.