There are several directional prepositions that are used in German (in, zu, nach).
Let's start with "in" and "zu". So if you wanted to say "I'm driving to the office", you could say "Ich fahre ins Buero." or "Ich fahre zum Buero.". The difference is that "Ich fahre ins Buero." means that you're actually going inside to work, whereas "Ich fahre zum Buero." means that you are driving to the office building or wherever you work, but you're not going inside or at least you're not going there for the purpose of working. "in" + article is used when you're going inside and for the actual purpose of this place, and "zu" + article is used when you're going to this place, but maybe not inside or maybe not for the intended purpose. What I mean by that is, if you're driving to the supermarket to go grocery shopping there, you would say "Ich fahre in den Supermarkt.", but if you're driving to the supermarket to meet someone in front of it, you would say "Ich fahre zum Supermarkt.". However, both can sometimes be used interchangeably.
The directional preposition "nach", however, is a horse of a different color. This preposition is reserved for countries, regions, cities, towns, and your own home. So you can say "Ich fahre nach Deutschland/ Bayern/ Muenchen/ Herzogenaurach/ etc.", but also "Ich fahre nach Hause".
"Hause" is a famous exception. Please note that "I'm going home" means "Ich fahre/ gehe nach Hause", whereas "I'm at home" means "Ich bin zu Hause."!!!
