To insert text within existing text, simply place the insertion point in the appropriate location (using the mouse or the keyboard) and begin typing. The existing characters move to the right as you type to make room for the new text.
To delete a single character to the left of the insertion point, press the Backspace key. To delete the character to the right of the insertion point, press the Delete key. To delete larger amounts of text, select the text and press the Delete key (see the next section to find out how to select text).