The above step will open the page in Edit Mode. Now From the RIbbon from the Editing Tools section click on Insert and then click on WebPart as shown in the figure below:
The above step will show you all the web parts category wise. From there select any web part. Here I am selecting a Content Editor web part from the Media and Content Category. After that click on Add as shown in the figure below:
Once you will Click on Add the web part will be placed in the page.
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