So you want someone else to come up with the story and setting? Why is is time period of interest too you? 

Also, those Natives in the picture are likely Apache or Navajo from the later 19th century. The Natives involved in the Seven Years War were living on the other side of the country, they were completely different tribes and there's over a century difference in the time period. That's like asking to do a Vietnam War RP and showing a picture of Napoleon's soldiers.