Complex sentence: Jamie made his debut for the GB & NI team at a Junior International in Salamanca, Spain, in 1991, winning the 200m and breaking the Welsh record in that race.
Split into simpler sentences: Jamie made his debut for the GB & NI team at a Junior International in Salamanca, Spain, in 1991. He burst onto the international scene, winning the 200m and breaking the Welsh record in that race.