@JTT,
Generally at this time of year, Momma kicks the little ones out and comes back to check on them - it forces them to learn to fly, but I would have picked it up too, had I found it on the road.
If he's hurt or scraped up a bit, you can use a wee bit of anti-bacterial cream like polysporin.
Get an eyedropper. Tweety will need water. They can get dehydrated quickly.
Dig up and mince some earthworms, find some bugs, like spiders (you're not superstitious are you)?. Slugs are great, if you're not squeamish, that is...Moisten cat or dog food and make it into a paste or buy baby food, they need a high protein diet -. you might also try frozen worms, little red ones - fish food.. can't remember the name, but thaw them out first and crush it up a bit.
Feed it with a chopstick or your finger. Make sure to get the food into it's beak gently.
Finally, talk, sing and whistle to the poor thing. And if you haven't got the time, call the local bird sanctuary. They can probably take him off your hands. or at the very least give you better advice..
Oh yeah, wash your hands a lot.