prove that a antisymmetric and invertible matrix is congruent to another matrix

Question

let A be an antisymmetric and invertible matrix $A \in M_{2m}(\Bbb{R})$

1. prove that A is congruent to $$ \begin{pmatrix} 0 & I_m \\ -I_m & 0 \\ \end{pmatrix} $$

2. prove that $-A^{2}$ is a positive matrix

thx