Sounds like me at the beginning.
Take 3 Scrap Metal and right-click on the red/orange box to the right of your inventory. That will make a Heavy gear, it is used in some beginning machines.
That's the crafting box. To make Furnaces and the like do the same, just with recipes from the book you can open with the TAB key.
Most food items and some building block items can only be made in certain buildings later, I would not bother with trying to make advanced food until you use a Yeast Bomb to get Tungsten and the buildings it unlocks.
(For Yeast Bomb: Make a Logic Switch, place it down, grab the Yeast Bomb, Control-left click the Logic Switch, place Yeast Bomb as close as you can to Tungsten. Flip Switch.) (I couldn't get the 'place item' method to work)
Lastly, to get Milk you just need to feed a cowgirl enough for a bar to appear under her and then shift-left click her for milk, I recommend Sweet Potato fries for early milk production.