Write the first four terms of the sequence $\left\{a_{n}\right\}_{n=1}^{\infty}$. \[ a_{n}=\frac{(-1)^{n}}{6^{n}} \] \[ a_{1}=\square(\text { Simplify your answer. }) \]

Step 1 ：Substitute \(n=1\) into the formula for \(a_n\).

Step 2 ：Calculate \(a_n = \frac{(-1)^{1}}{6^{1}}\).

Step 3 ：Simplify to get \(a_1 = -\frac{1}{6}\).

Step 4 ：\(\boxed{-\frac{1}{6}}\) is the first term of the sequence.