已知\(F _{1}\)，\(F _{2}\)分别为椭圆\(C\)：\( \dfrac {x^{2}}{a^{2}} + \dfrac {y^{2}}{b^{2}} =1(a > b > 0)\)的左右焦点，点\(P ( \dfrac { \sqrt {6}}{2}, \dfrac {1}{2})\)在椭圆\(C\)上，且\(|PF _{l} |+|PF _{2} |=2 \sqrt {2}\)．
\((1)\)求椭圆\(C\)的方程；
\((2)\)设\(A\)为椭圆\(C\)的左顶点，过点\(F _{2}\)的直线\(l\)椭圆\(C\)于\(M\)，\(N\)两点，记直线\(AM\)，\(AN\)的斜率分别为\(k _{1}\)，\(k _{2}\)，若\(k _{1} +k _{2} =3\)，求直线\(l\)方程．