Superficial dirt on the display is best cleaned with a TFT monitor cleaner and a microfiber cloth or other non-aggressive cleaners.
The internal cleaning requires opening the notebook. Note that this process varies from device to device and may void the warranty. If this is too delicate for you, use a vacuum cleaner on low power and carefully vacuum over the fan outlet and keyboard. When you open the device, use a brush to remove dust from the cooling elements and components. Alternatively, you can also use a vacuum cleaner carefully. The keyboard is best cleaned when it is removed.
If possible, avoid using liquids and spray cleaning agents directly onto the microfiber cloth. In the worst case, this could lead to electronic damage. If you want to be on the safe side, contact a service shop near you.