In the case you live far away you would like to take an airoplane. You may fly to Wien, Bratislava or Poprad. Flights to Poprad are limited only from London by Sky Europe (as far as I know).

You can see route from Bratislava to Demänovská Dolina, the nearest village to Chopok, at the site ViaMichelin. Click the link or just write there start and finish. You can see route from Poprad to Demanovska Dolina same way.
From Demanovska Dolina to Chopok it's easy just folow the road signs.

All maps at this site are from ViaMichelin website.