Why are the people refusing to eat

1.) The hopper must be facing the correct direction. The side of the hopper that must face the dispenser is the wider side without the black line on the texture (the open side).

2.) It may simply be a glitch in the AI or a general bug, as the game is early in development - especially when this was asked.

Rescue: Left click a healthy colonist to select them. Right-click the sick or injured colonist to open the context menu. Left click "Rescue [name], [title]" to order the colonist to rescue them. You will need an empty bed or sleeping spot that you've marked for hospital use for this to work, otherwise the colonist won't know where to take the patient.

Eat where you want them to: How far a colonist will look for a table and chair to sit and have their meal depends on how hungry they are. If they're just kinda hungry they'll walk with their meal a decent distance to find a good place to eat. If they're taking starvation damage they'll carry whatever food they find a few steps max before they start devouring it. I suggest making a small, high-priority food stockpile near the table you want them to use, or just storing ALL your food in a freezer near it.

Sleep where you want them to: Build a bed (or sleeping spot), click the bed to select it, at the bottom of the screen click "Set owner", choose the colonist you want to sleep in that bed. Note that no matter how tired they are or how far from bed they are, they will walk all the way back every time they go to sleep, so if you have them doing work a long way from home for a while, you might want to change their owned bed to one nearer the work.

General navigation stuff:

• It's a little counter-intuitive, but to have colonists interact with things that are constructed, you usually pick the thing first and use one of its menu options to interact with the colonist (like the bed example above, or setting a "bill" for item production in a workshop).
• To have a colonist interact with a piece of equipment, another colonist, or a visitor, you select the colonist and then right-click on the the thing/person you want them to interact with (like the rescue example, or for equipping gear).
• To have a colonist interact with the environment, you usually use the "Orders" tab in the architect.
• To have a colonist interact violently with something or someone (besides hunting, that's "Orders"), you pick the colonist, draft them using their menu, and then can use right-click to move them to specific locations (they will fire around corners, using them as cover) or order them to attack specific targets.