Ten kilometres is the distance where running starts to feel like a sport. It is long enough to need a plan and short enough that almost anyone can get there in eight weeks.
Run three times a week. Make two of those runs short and easy, at a pace where you can hold a conversation. Make the third run your long run, and add about one kilometre to it every week until you reach nine.
The one rule is to slow down. Most new runners go too fast on easy days and then have nothing left for the long run. If you cannot speak in full sentences, you are going too hard.
In weeks five to seven, add a little speed to one of the short runs: six bursts of one minute fast, with two minutes of easy jogging in between. It teaches your legs to turn over quickly without wearing you out.
In the final week, cut every run in half and rest for two days before the race. Start slower than feels right, and save your effort for the last two kilometres.