Drivers need to pay attention to a lot of things all at once, such as: the road, the traffic, and their speed, not to mention being on the lookout for pedestrians and potholes.
You can express all this in one of two ways: briefly, or with details.
Briefly, you could say something simple, like:
When you're driving, you should remain alert.
When you're driving, you should pay attention.
When you're driving, you should stay focused.
If you want to provide more details, I'd be careful about using a single phrase such as "to the front" – after all, wouldn't you want the driver to check their mirrors every now and then? That's why I think the only way to elaborate a little more is to provide a lengthier list, such as one of these:
When you're driving, you should:
pay attention to the road while staying aware of your surroundings.
keep your eyes on the road but remain cognizant of what is going on around you.
look ahead, and remember to employ defensive driving techniques.
ELL is focused on learning English, not driving skills, so I don't want to delve too much into safe driving practices. But I was careful to sprinkle some idiomatic expressions in this answer that might be useful to the learner.