Working out just where to start telling a story is quite a challenge. If you start too slowly and include too much backstory, the reader is likely to get bored as they wait for the action to start. But if you start too fast, the reader can get confused and give up.
You have to seize your readers’ interest in the first couple of pages. My stories tend to start with the heroine, but within the first couple of pages she meets (or meets up again with) the hero. Immediately these two are faced with a challenge, a change in circumstances or some kind of conflict. The reader knows they will end up together but needs to start wondering right from the beginning how on earth that is going to happen. You have to make them curious enough to want to read on.