Go to the menu Rates and selections New rate. You will see all the articles by families. Enter in the top menu the Name of the new rate and select whether the prices include taxes or not. Also, at the same level, you can select the family of items that will be displayed below.

Enter a price for each item. If multiple items have the same price, you can select the checkboxes at the beginning of each item's line, then click the price field, to assign the same price to all selected items.

If you already have a rate created, when you want to add a new one, you can choose whether to copy the items from another rate and whether to increase (positive) or decrease (negative) the prices by a percentage or a specific amount. This way, it will not be necessary to manually recreate all the items.