Building a CNN class

I need help to build a CNN class with the following architecture:

(1) Input: 26

(2) 1D convolution: 256 output channels and a configurable kernel size(specified as an argument to init)

(3) Relu

(4) 1D convolution: 256 output channels and the same kernel size as the 1D convolution at position 1

(5) fully connected layer: 25 output features

(6) output: -