You should post your code...
Im assuming this is a binary tree... heres the pseudocode
findString(RootNode,StringWeWant){
if RootNode == StringWeWant{
WERE DONE
}
else if RootNode < StringWeWant (string comparison){
findString(RootNode.rightchild, StringWeWant)
}
else{
findString(RootNode.leftchild,StringWeWant)
}
}
So as you can see this is a recursive function you can create that tests the root node initially to see if it is the string we want to find. If the root node is less than the string we want, we want to traverse right. If its greater, than traverse left. We can call the same function but pass in the new node we want to compare it to till we find our string we want.
Hope it helps.