Primarily, the mouse is used to move around the spreadsheet.  To move to a cell (i.e. make it the active cell) simply click on that cell.  To select a block of cells, click on a cells and drag the mouse to select multiple cells (selected cells appear in black).  With a block of cells selected, you can then change the font, border, color, etc..  of all selected cells with a single command. 

The following table displays the keystrokes used to move in the spreadsheet.

[Up Arrow]	Move up one row
[Down Arrow]	Move down one row
[Right Arrow]	Move right one column
[Left Arrow]	Move left one column
[Shift+any arrow key]	Extends selection in direction of arrow key
[PgUp]	Move one page up
[PgDown]	Move one page down
[Ctrl+PgUp]	Move one page left
[Ctrl+PgDown]	Move one page right
[Home]	Moves to the first cell in the current row
[End]	Move to the last cell in the current row with data
[Ctrl+Home]	Move to cell A1 (upper left corner of spreadsheet)
[Ctrl+End]	Move to last row and last column that contains data
[Shift+Space]	Selects the current row
[Ctrl+Space]	Selects the current column
[Enter]	Move right one column