I am aware of the theory of needing 6 mini meals a day instead of 3 big meals a day in order to lose fat (I'm skinny anyway) and to bulk up (my target).

I'm also aware that obviously the mini meals must be healthy. I'm thinking would eating some fruit and a yoghurt at points inbetween the meals be enough to kick the action into effect or is more needed.

ie. A bannana in between breakfast and lunch. Would that count or is more needed?

IF your skinny, you want to gain muscle. Six meals a day is good, but focus on getting protein first. I use to weigh 117 now I weight 160. Get about 150g of protein a day. Spreading that into six meals will help. Get some gold standard whey.

The idea behind these "mini meals" is to keep your metabolism active throughout the day. Combine this with regular exercise and protein shakes and you are golden.

eat 3000-4000 calories with 135+ grams of protein everyday get a good amount of carbs and fats and you will gain muscle if you are consistently working out every week. dont do cardio for a couple months. you dont have to eat so healthy since your're bulking especially cus you are an ectomorph. you can pretty much eat whatever you want but try to eat healthy most of the time but junk food isnt a bad idea in your case just so you can stay at a calorie surplus. dont drink your calories, learn to make water your best friend, everywhere you go have a glass or bottle of water with you.