Your dog needs to rest,dont feed him anymore.Until he's hungry.If he has a uspset tummy,you should cuddle him and his tummy.But most importantly..Take him to the VET. please :) Let him drink water,its better.Lay off the rice for a while. If he keeps on vomiting for the next 5 minutes or less..then yeah,give him a teaspoon..other than that..GOOD LUCK! :)
Don't give him any food, for now. If he has an upset tummy, he needs to rest from food. As long as he's drinking he'll be fine if you fast him for at least one meal. Then start with a little boiled rice and chicken breast, and you can add a little natural yogurt too which helps settle uncomplicated tummy upsets.
However, if he really is throwing up blood, you need to get him to a vet asap. It could be just bile however, so don't panic. Just don't pile in more food, for now. Chances are if he's doing this, he's not going to be interested in food in any case.
Obviously if your dog is very young this is more serious, and he will need to see a vet as soon as you can get him there.
Can you call your folks on a mobile phone? The rice may help but depending on what is wrong sometimes it is better to starve them for 24 hours, Speak to your vet on the phone and see what they say.
Is he drinking excessively? Is he lethargic? These can be symptoms of Parvo. If he is in pain (stretching a lot with a tummy ache) it may be the start of bloat. These are wose case scenarios. Speak to your vet.
My dog actually has had bad throw ups before from eating candy and so forth and so white rice is a very good thing to feed your dog and if you can put in some chicken watch him at all times after you feed him and dont get to mad if he throws up again infact hope that he throws up as much as he can so that he can get rid of the food etc or whatever it was that he ate. Good Luck!
Call your vet NOW. How old is the dog?