Navigate to the course and open the Gradebook from the course Administration menu
Open the "Categories and items" page. If your gradebook uses tab-based navigation, click on the tab that says "Categories and items." If your gradebook uses a dropdown menu, locate "Categories and items" and select "Simple view."
Set the course Aggregation to "Weighted mean of Grades."
Enter the weighted values you wish to apply to your assignments. A value of "30" will cause that item to be weighted 30%. You can assign a weigh to an assignment individually, or to an entire category.
If you assign a weight to a category, then note that the individual category's aggregation strategy does not need to be set to "weighted mean of grades." Instead, the category-level aggregation may be set to "Sum of grades."
Be sure to click "Save Changes" at the bottom to save your weights.