Infancy and toddlerhood are the formative years in a child's relationship with food. These years should be full of exposing him to wholesome, real foods in child-friendly form several times a day.
Real foods meaning whole foods- fruits, vegetables, full fat (preferably farm fresh) dairies and eggs, (preferably grass fed, all natural) meats and whole grains after 9-12 months. This does not mean the easy to-go foods in the baby food aisle. Freeze dried yogurt puffs, dried fruit twists and corn puffs do not constitute as wholesome, real foods! Child friendly form simply means they are in smaller sizes, easy to hold and easy to bite from. They may be in stick form with dips available, too. Toddlers do love to dip! Served to him several times a day so he can follow his natural cycles of hunger, as little ones do have a fast metabolism and are easily distracted from eating.
Select a variety of flavors, textures, smells and colors for him to eat. Our society heavily tends towards sweet and salty flavors but there can be so much to enjoy with vinegary, savory, spicy flavors even for a toddler! Expose him many times to a new food and let him see you eating and enjoying it, too. Don't fret if he isn't getting all his food groups perfectly eaten in one day. Instead, look at his nutrition over a few days to a week span. Keep in mind that toddlers can tend towards particular foods for a while and may possibly just need something nutritional from that food for a period of time.
Lastly, habits such as sitting at the table for a whole meal, scheduled snack times, etc. should be saved for preschool age or beyond. Toddlers are much to absorbed in their world of new things to explore and do and should not be expected of any sort of eating schedule yet. What's most important is that you set the foundation for that by inviting him to sit with you for meals and snacks and making them an enjoyable experience of togetherness.