Where? At last, click Apply button to execute changes.
Found insideThis book will help you in deploying, administering, and automating Active Directory through a recipe-based approach. As Al wrote, the 5-15MB of unallocated space need to be located in the end of drive boeing accelerated (I assume that in your case it is drive C:).
If you don't have the string in Topics, it could be under Titles.