Follow these steps to accomplish the missions successfully:

1) Each mission must be reported to the Ministry of Time.

2) In the report you will have to: describe the Earth as it was in that moment of the past (flora, fauna, temperature, relief, oceans,....), describe your route (remember: just three leaps in time), describe the way you will fulfill the mission (using creativity and scientific knowledge). 

3) Each report will have a different layout, your superior will let you know.

4) You can find here some useful websites to complete your missions.