Go simple. Food pyramid is easy to find on google and will show you what to eat in proportion. You may need to tweek it a bit to suit your trianing but most should be close to this balance.
There are a few ways to eat more food, one is browsing the other is stealth eating as I called it.
I had to up my intake years ago and these were what I settled on. I still browse to this day, eating whenever I am awake and not too close to training. Disappointingly no-one has come forward with ideas on eating in my sleep, and I have asked on a few occasions.
Browsing. Rather than eating a set number of large meals just have food available all of the time and keep eating. I have a box of food, often repetetive diet, on my desk with a fork in it, and I take frequent mouthfuls to consume more than daily intake of calories for average man during working hours. This system means you are rarely hungry and never full. Typical browsing food for me is rice with eggs, pasta and tuna, with side order of raw veg like carrots or fruit.
I have worked somewhere that talked about stopping eating at desks, but fortunately I was one of the smallest who objected to that and we pointed out that people getting between us and food get eaten. Food at desks was back on the menu.
Stealth eating. Basically putting food into liquids or eating denser foods. Light fluffy cakes can be pretty and sweet. My old calorie cake was far from it, ingredients were, flour, butter, oats, seeds, vanilla extract and corn syrup which is sweet but contains a good deal of complex carbs better than sugar. The end result weighed about double for volume of a prize winner, but tasted good and was loaded with calories and easy to carry around.
Water was replaced with a very wet mix of milk, oats and occasional hint of corn syrup. So even when drinking I was still eating.
My current diet is 4,500 to 5,000 calories a day, though with being a bit excessive over christmas and new year and doing virtually no training, I may need to drop this a few hundred for a month or so, to avoid being chunky old man.
I have eaten more, most I think was about 6,500 a day for about a month when my activity level was so ridiculous that I was still losing weight for the first couple of weeks, got it back quickly enough. I literally couldn't eat more at that time, due to activity level and duration, but I knew it was only for a few weeks.
