Heres a nice template for recursion
public <modifier> recusiveAlg(You need some sort of parameter)
{
if(some sort of stopping criteria)
{
return something;
}
else
{
return recursiveAlg(your parameter - 1)
}
}
Try to do this with Fibonacci numbers
hint: Fibonacci's numbers are the previous fib number + the one before the pervious fib number.