等差数列\(\{a _{n} \}\)的前\(n\)项和为\(S _{n}\)，且\(a _{3} =9\)，\(S _{6} =60\)．
\((1)\)求数列\(\{a _{n} \}\)的通项公式；
\((2)\)若数列\(\{b _{n} \}\)满足\(b _{n+1} -b _{n} =a _{n} (n∈N _{+} )\)且\(b _{1} =3\)，求数列\(\{ \dfrac {1}{b_{n}}\}\)的前\(n\)项和\(T _{n}\)．