It's simple. Break it into several /say commands:
Code:
test {
  say Here are the steps on how to unlock and open car door
  say step 1: get the key for the door lock
  say step 2: insert key into door lock
  say step 3: rotate key clockwise untill it will not rotate
  say step 4: pull door handle up untill door opens.
}


If you wanted, you can write the alias in one line, separating the commands with a pipe - |. However, it costs in readability.
Code:
test say step 1... | say step 2... | say step 3...