To change the appearance of selected cell(s), row(s) or column(s) use the Cell Format... option from the Format menu or from the right mouse button pop up menu. This will bring up the Cell Format dialog box which has several tabbed pages:
The Border page lets you set the appearance of the cell borders. If you have selected more than one cell you can apply different styles to the borders between the cells and that surrounding the selected area.
First select the pattern and color from the Pattern section of the Border page then apply that to different parts of the border by clicking on the appropriate button in the Border section, or on one of the Preselect buttons. The left hand button in the Preselect section will clear any previously applied border(s). Note that you can also add a diagonal strike-through line to the cell(s).
The Text page lets you select the font style, size and color, the cell background pattern and color can be selected from the Background page.
From the Position page you can control the position of text within a cell by making suitable selections in the Horizontal and Vertical areas or by setting the Indent value. You can also choose to have the text appear vertically rather than horizontally, or even at an angle.