Not all of the lines in this text have an urgent tone, so they are not called "important." "Passage driving is a lot of work. Many things must be done if you drive to make sure your car is safe." One way to change this passage so that it is in the imperative mood would be to: "Passage driving should be a big deal. To make sure your car is safe to drive, you must do this:"
An imperative mood is shown in a passage when the speaker of the passage is giving an order or making a request to the person who is going to do it. To make a request, invitation, exhortation, command, advice, or supplication, all of the verbs in the text must be used together.
When someone reads this passage, the first two sentences need to be changed so that the whole thing sounds like an order. This shows what a person should be doing to get a good direction.