[subject] + 到 + [place] [subject] + 到 + [place] + 去 / 来 [subject] + [verb] + 到 + [time / place] 从 + [A] + 到 + [B] [verb] + 到 (result reached)
到 marks an end point. As a verb it means "arrive"; after another verb it says where the action ended up or when it stopped.
When 到 introduces a destination before the verb, the sentence closes with 去 or 来. 去北京 says the same thing more briefly.
After a verb, 到 + a time says how long the action went on. With 从 in front, it closes a span of time or distance.
At the front of a sentence, 到 + a time sets a deadline: "by then".
Attached to a verb, 到 says the action reached its target. 看到 is to catch sight of, 听到 to catch the sound, 找到 to find.
The negative is 没, not 不: the action did not reach its result.