Hello friends,
I am going to show you How to Suggest an Edit in Google Docs
First let me tell you something: You can not suggest an edit on Google Docs if you do not have this permission given by the owner of the document.
I already provided this permission on a test document.
If you have this permission available you will see in the right part the text Suggesting.
To make a suggestion just click where you wish to make this and start editing like a normal document. This will send automatically a new suggestion to edit for the owner. He can accept it or reject it.