Which preposition should I choose in this case and why:
e.g. This is what I wore to work/at work yesterday.
But I don't get why 'to' is correct.Could you give me a further explanation,please?
I wore this when I went to work.
That one is fairly straightforward. In general, however, there is little point in asking why we use certain prepositions in certain phrases. Prepositions are a law unto themselves - in most languages that have them. We watch things on television, the French watch things at the television, and Germans watch things in the television. That's just the way it is.
Context is always important; labelling is rarely important.