You need to use
while(cin >> x) myVector.push_back(x); // ^^^^^^^^^
std::vector::insert(), which, as you can see in the link, needs an iterator to indicate the position where you want to insert the element.
Also, as what @Joel has commented, you should remove the parentheses in your vector variable’s definition.
By doing the latter, you run into C++’s Most Vexing Parse problem.