1, insert the shape. Position the cursor at the position where a horizontal line needs to be added, click the Insert menu, select a shape, find a vertical line, select an appropriate horizontal line style, such as a line or line, hold down the Shift key to draw a horizontal line, and then adjust its length and position by dragging the control points at both ends of the horizontal line.

2. Use the underline function. Enter spaces or spaces that need to be added with horizontal lines in the text, select these spaces, click the underline function in the start menu, select the appropriate underline style, and then press the space bar until the desired horizontal line effect is formed.

3. Use the border function. Insert a text box or table where you need to add a horizontal line, select the text box or table, click the "border" function in the start menu, select the appropriate horizontal line style as the border, and then adjust the size and position of the text box or table.

4. Use shortcut keys. Press the minus key "-"on the keyboard where the horizontal line needs to be added, then press the space bar to extend the horizontal line to the required length, and finally press Enter to complete the insertion of the horizontal line.

5. Use the horizontal line tool. Look for the Insert or Shape option in the WPS toolbar or menu, and select the Horizontal Line or Horizontal Line option to insert the default horizontal line in the document.