已知数列\(\{a _{n} \}\)中，\(a _{1} =1\)，其前\(n\)项和为\(S _{n}\)，且满足\(a _{n} +2S _{n} S _{n-1} =0(n\geqslant 2)\)．
\((1)\)求证：数列\(\{ \dfrac {1}{S_{n}}\}\)是等差数列；
\((2)\)记\(b_{n}= \dfrac {1}{2n+1}S_{n}\)，求数列\(\{b _{n} \}\)的前\(n\)项和\(T _{n}\)．