One way is to right click on the cell, click on Format Cells, Click on
Alignment, click on wrap text. This will keep your text within the cell
borders, but will of course stretch it vertically
Another way is to press <Alt><Enter> where you want it to wrap. This means
that your text will not necessarily remain within the cell boundaries.
Another way is, after you have pressed <Enter>, to return to the cell,
select a range of cells, whether in one row, or in several rows, where you
think the text will fit (e.g. with your text in A1, select A1:G3), now click