It means writing and of course before...

• you have carefully read the task
• you have watched the five concepts (context, variation, purpose, meaning and audience)
• you have decided the type of text from the three proposed
• you have generated ideas and classified them in main and secondary
• you have structured and organized what you want to write.

About the writing, some suggestions:

• If you start a sentence and you doubt about constructing it properly, stop and think of a different sentence which can be easier for you. 
• Decide the main tense you are going to write and be consequent. Of course, you will use two or three different tenses (the variety of tenses are extra points for criterion A), but be careful how you combine them.
• Choose the more adequate variation (formal-informal) for the task and stick to it along the text.