You forgot the return types in your member function definitions:
int ttTree::ttTreeInsert(int value) { … }
^^^
and so on.
Your declaration is int ttTreeInsert(int value);
However, your definition/implementation is
ttTree::ttTreeInsert(int value)
{
}
Notice that the return type int is missing in the implementation. Instead it should be
int ttTree::ttTreeInsert(int value)
{
return 1; // or some valid int
}