the exercise instructions give a template for you to follow:
element {
property: value;
}
So you need to write the element first (in this case the instructions say the element is h1).
Then you need to write the left curly brace and press enter
then write the property (in this case the property is text-align)
then write a colon immediately following that then one space
then write the value (in this case the value is center).
then press enter and write the right closing brace
If you use the template to guide you, you should produce proper css code.