We can create a general discount that covers certain types of clients, groups etc. at the time of making any booking from the menu:

Customers --> Offers and discounts --> Global Discounts.

To create a new discount we will press the New button, name it and save it.

Then we edit it and go to the section: "To whom does it apply?" in which we indicate the condition with which the discount will be applied. For example, if we have a type of client that is called "Retired" we will look with the magnifying glass for that type in the "Type of clients" section and without selecting anything else we will give you Insert.

Once we have selected to whom we will apply the discount, 

Enter the "Discounts" tab on the left menu and give it to "New":

In this window we indicate the percentage of discount to apply, in which category we want to apply it, or if it is for all the services offered by the club, and if we have selected a category, in which services of this category should be applied.