The Cellar - Baby squirrel

Jinx, if you found the squirrel near a tree with the nest, (within the span of a tree's branches) you might want to try putting him where you've found him and staying within sight, in order to keep an eye out for cats or hawks.
If the mother isn't injured, there's a good chance that she'll come back and carry him back to the nest.

If that doesn't work, go to a pet store and ask to buy a damaged aquarium. Explain what you need it for. I got one with a slight crack and they included a caged lid with security clamps for five dollars.
Squirrels like to sleep in things like large work gloves, very large socks or crown royal pouches. Put some dead dry leaves or torn facial tissue in the bottom and then put in his "bed". He will climb in/under his bed if he's old enough. Replace his bedding when it's damp.
If his eyes are opened, he's probably about 2 1/2 to 3 weeks old.
You can give him formula (3 oz. whole milk and 1 tsp. of baby cereal) with a plastic (not glass) eyedropper. Make a fresh batch each day and avoid heating any hotter than body temperature before feeding him. Clean the eyedropper well after using it. Also avoid hamster shavings for bedding and bathing. All three can cause them to get colds or pneumonia.
When his eyes open, if they aren't already, start feeding the formula from a dish/jar lid in an area separate from his bed. In the bottom of the dish put some bread in it and then add the formula and let it sit a few minutes to soften it. Put the dish against his mouth if he's not sure what to do. It might take a few tries. If he gets messy, just dry him with a rag. When he seems more mobile put a small piece of branch propped to give him climbing/grasping practice. At this point he will be also ready to have a water bottle in his cage. When, just like a baby, he seems not quite satisfied with his formula start adding hammered acorns, raisins, apple slices, peanuts, sunflower seeds and some birdseed. At this point, you won't want to handle him much more than necessary, as when he's released he'll be less wary of predators.
When he's about eight weeks he needs to acclimated to the outdoors.
Eventually, you'll be placing his home outside or on a screened in porch and leaving the cage open during daylight hours and putting the lid on after dark. If his home sits outside try to situate it out of the elements in order to keep it dry and out of the exposure of wind.
By looking at the picture he looks somewhat young. You may have to winter him over inside (utility or laundry room, garage, enclosed porch) because he might lack experience and/or have had time to store his own food. Make sure to give him lots of extra bedding.
In order to determine whether he needs to be wintered over, compare his development with other squirrels: is he collecting food?, does he show an interest in making his own nest?, does he socialize?, does he climb well?, etc. He might end up being able to nest, but continue to need food put out on a nearby platform (tray feeder, picnic table, an old cookie sheet with punched holes - much sure holes are punched from the top so that the metal ends are on the bottom)

Good luck! Let us know how it works out!