F8 or T
Once the Text tool is active, you will have two options at your hands about how to create a text.
When you want to add a text that consists only of a single word or a short expression, the easiest way to add it is to:
Left-click on the canvas to place the cursor at the desired position.
Type the text directly afterwards. The text will all be put into a single line, unless you hit Enter to continue in the next line.
When you want to put your (longer) text into a specific area that you have reserved for it:
Click-and-drag on the canvas. This will create a frame for a flowed text with a blue border, in which the text can be inserted.
Type on the keyboard. The text will appear in its frame and will not leave the frame area. When it reaches the border of the frame, it will automatically flow into the next line. The border of the text frame will turn red when the text doesn’t completely fit into it.
You can change the dimensions of the text box by dragging on the white handle in the bottom right corner.
The text will not stretch or grow to fill the allotted space at all costs. It is up to you to adapt the size of the area or the font to your needs.