If editing a simple* page place your cursor where you wish to insert the image and click the Add Media button
Tick to select the desired image and select suitable image size and alignment.
TIP: Avoid selecting a larger-than-needed image size as this will slow down loading of the page for website visitors. In most cases image width of max 1000px will be more than enough.
* If inserting images via the Avada Builder you will access the media library in a different way, but the principle of avoiding use of overly large images remains equally important.