My first Championship was won in 1934 with the Club 'AJAX' of the second division of the Curacao Soccer Federation.

I was co - founder of AJAX, thus it was in the first and last year of the club in the Soccer - Federation. My second club was R. C. C. 'Racing Club Curacao' in 1936 of the first division of the soccer Federation of Curacao. It was the first championship of R. C.C. in the first division and it was my first year in the team, it was also, an unbeaten soccer championship.

In 1937 ( then I was living in ARUBA), I founded a club: "A.B.C" "Aruba Best Club" with a group of youngsters.

I played about a year in A.B.C. but being an ambitious person and a good player, I convinced the other players to aim higher. As I came from the Racing Club Curacao (R.C.C.), I proposed to the other members to change the name, :A.B.C." in "Racing Club Aruba" (R.C.A.) and so it was done. We changed the colours also, and very soon we were promoted to the first division of the Soccer Federation of Aruba.

We won the two championships as an unbeaten champion in our first and second year in the Federation. It was 1938 ending 1939 and the Start of the world-war in Europe, I had trouble with R.C.A. and with a group of friends from Curacao I formed a soccer club under the name of " Independiente". We challenged R.C.A for a match and beat them 3-0, and embarked to Curacao the next week.

Maybe that our reputation as a good team, gave us with "Independiente" the opportunity to enter the Soccer Federation of Curacao in the first division without playing in the minors.

In 1942-1943 playing for the first time and in the first year of 'Independiente' in the first Division, we became unbeaten champion. Beside being a player also i have been a linesman local Refree, International Refree in Curacao and Refree-Instructor for The F.I.F.A. (The International Amateur Soccer Federation). I furthermore performed as a coach for soccer in five games in 1946 in Curacao for the National team and in four games in 1943 in Surinam all unbeaten.

In 1941 I played in the first Championship of the Caribbean and the Central America in Costa Rica as center-half for Curacao. We finished in the third place, Costa Rica was the unbeaten champion

Guillermo E. Rosario as captain of the Curacao team at the inaugural game of the first Central American and Caribbean soccer championship, along with the captain of the Panama team the referee and the president of costa rica His Excellency Dr. Rafael Calderon Guardia, who did the initial hick off.

This is the curacao team that participated at the first Central American and Caribbean soccer championships, Which took place in San Jose Costa rica in 1941. curacao finished in third place.