Edge cutting

I want to just do edge cut but the app asked what edge to set cut first ? Any ideas how to do this ?

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Good morning, thank you very much for your feedback.  Started mowing: trim the outer contour edges of the map (you can choose to specify the edges of the designated area or the charging station). Please select the edges you want, such as the edges of restricted zones or the edges of all lawn areas, then tap Start, and you are good to go. Feel free to reach out to us anytime if you have further questions.