Bowling Pins are located in the Top Gear Challenge events in Season mode, via the Event list or in certain Rival events.
Gold pins are usually located either halfway through or near the end of events and are usually few spread out in places you may not venture on a normal run.
A fast way to get this is after doing the tutorial race and receiving your first car head into the Events list (Via Play Career and 'Go Race') Head right till you come to the Top Gear Challenge event and select the first one.
The first gold pins are located after the first 'hairpin' turn, there will be 3 of them at the front, hit one and the achievement is yours.
Here's a video demonstration.