The easiest way to pause is to press the pause icon in the menu. A pause symbol with a dot like this will be inserted.
An alternative method is to insert a break tag and specify the pause length in milliseconds. Press the SSML button in the menu, then break.
This inserts a tag with a minimum pause of 200mm, like this: <break time="200ms"/>
This means that there will be a 0.2 sec pause. If a 1 sec pause is required, specify <break time="1000ms"/>. 1000ms = 1 second. This tag is very useful to control pauses of different lengths.
In the example below, a tag was inserted for 2 seconds <break time="2000ms"/>