Hi Olgie,
Eating 5-6 small meals a day is a very sound and potentially successful strategy for healthy weight loss.
Your body handles smaller amounts of food better than big meals and is more likely to use the energy contained in the food, rather than store it as fat.
Also, eating small amounts every 3 hours keeps your metabolism fired up and helps prevent your body slipping from fat burning to fat storing mode during long gaps between meals.
You also burn energy when you eat - the thermic effect of feeding (TEF) - so you'll burn a percentage of the calories in each meal simply by eating, digesting, assimilating...
Certain foods require more energy to digest, protein for instance than others -say carbs, which are easy to breakdown. As such, try to ensure you include some protein in every meal.
Regular meals also help to balance your blood sugar levels and help to prevent cravings and overeating.
As the others have said, take your daily calorie allowance and divide by 5 or
6. For example, 1,500 calories a day equals 5 x 300 calorie meals. However, each meal doesn't have to be exactly the same number of calories.
I would suggest, using the same 1,500 cals example, breakfast, lunch and dinner at say 400 calories each, with a mid-morning and mid-afternoon snack of 150 calories.
This may work better for you simply because you're likely to have more time to sit down and eat at regular mealtimes than during a morning or afternoon break.
If you can eat 5 or 6 similar size meals, then great, but don't worry too much if you can't. A banana and a low fat, sugar free yoghurt as a mid-morning snack is fine.
Hope this helps,
Kind regards,
Marcus