To add text to a cell you click on the cell and begin to type.  In the A1 cell type SampleGrade Sheet.

As you type the text it appears in the box next to the three symbols a X, a check mark and the symbol for adding a formula.  

Once you have completed adding the text you can go to another cell to continue work on your spread sheet.  This can be done by clicking on the check mark. by hitting one of the four arrow keys on the keyboard or by hitting the tab key.  The example below shows what happened when I hit the down arrow key.

Notice that the words you typed are now in the first cell. Also notice that they look like they extend into the second cell, this is not the case.  Notice also that cell A2 has the black box around it indicating this is the cell I am working in.  In this cell type Fall  Semester 2014.  The spread sheet will look like this.

The next thing to do is create the column and row heading.  In this case the column headings will be

The row headings will be

Once you have completed the row and column titles enter the following data.

Date modified 09-07-14

Your spreadsheet should now look like the one below.