Air Force survival manual, Boy Scout wilderness manual, any survivalist web site...

Hard to believe anyone with an internet connection can't find any information they need on this.

Fire, water, shelter, food, in that order.

If people will be looking for you, stay put. If not, walk downhill until you reach water, follow it downstream and you will eventually find civilization.

To find out if it's edible, rub some on the back of your hand and wait an hour. If no reaction, rub it on your lips and wait another hour. If no reaction, rub it on your tongue, same deal. Then chew and spit out. Then eat a tiny amount. Then you can figure it's at least not instantly deadly.

Lots more info out there...