Using Poke Radar for Pokemon GO is extremely simple. You can view all of the nearby Pokemon in your area that have been discovered by your self and other players on the map, along with the times of day they were found.
If you're trying to find a specific Pokemon's location, you can quickly use the "Filter" feature to find the nearest one.
Since Poke Radar for Pokemon GO is driven by it's community, it's possible that there may not yet be Pokemon locations in your area when you first download the app. If this is the case, you can go out and mark the locations of Pokemon you've found to help other players in your area. When others view the location of the Pokemon locations you've marked, your trainer name will also be associated to aid your local trainer reputation. Everyone's gotta catch'em all - so why not work together?