You can make a Table reservation contacting the restaurant directly, either by phone, email, or through their website. It's always a good idea to make a reservation in advance to ensure you can get a table at the time you want, especially if it's a popular restaurant or a special occasion.
In terms of timing, it's generally recommended to make your reservation at least a few days in advance. It is common for some restaurants to require a deposit or credit card guarantee for larger group reservations.