Silicone sealants are available in tubes of varying sizes; the most versatile are the clear variety which will blend in easily with any style of kitchen. The tubes usually have a disposable applicator in the pack, though a decorator's gun (if you have one) is more robust and will come in handy for other jobs around the house. If you don't have a decorator's gun it might be worth investing in one when you buy your sealant.
The kitchen silicone sealant tube will have a nozzle which you will need to cut to apply the material. Using a sharp knife cut the end of the nozzle to the required size try to keep this as small as possible to achieve a neat finish and avoid wastage. Apply the silicone by pressing down on the trigger and keep the pressure as even as possible to avoid creating lumps or bulges of sealant. For each gap to be sealed, try to apply the silicone in one single application. This keeps the bead of silicone neat and smooth and again avoids wastage.
Once applied the sealant can be smoothed off with a cloth, plastic tool or your fingers! As silicone is not water based it does not 'dry' but sets through a chemical reaction with the air. This makes silicone an ideal material for working in kitchens or bathrooms where the humidity in the air may affect other types of products.
Different silicones will have different curing times, though most modern silicone products will cure very quickly, check the manufacturer's instructions as to how long you will need to give the material for it to be fully 'cured'. A good kitchen silicone will help to eliminate cracks that can allow bacteria to thrive and most silicones will have antibacterial elements added to them. In the long term kitchen silicone will make the cleaning and maintenance of surfaces easier. Kitchen silicones have a long life time, though if damaged areas develop over time the material can easily be removed and replaced.