diff --git a/neuralNetworkTests.c b/neuralNetworkTests.c
index 21ab370..5173fa2 100644
--- a/neuralNetworkTests.c
+++ b/neuralNetworkTests.c
@@ -6,11 +6,46 @@
 #include "neuralNetwork.h"
 
 
+
 static void prepareNeuralNetworkFile(const char *path, const NeuralNetwork nn)
 {
-    // TODO
+        //öffnet die Datei in Binär zum schreiben
+        FILE *file = fopen(path, "wb");
+        if (!file) return;
+        //Fester Headerstring
+        const char *tag = "__info2_neural_network_file_format__";
+        fwrite(tag, sizeof(char), strlen(tag), file);
+        //Bestimmt die Eingabedimension
+        int inputDim = nn.layers[0].weights.cols;
+        fwrite(&inputDim, sizeof(int), 1, file);
+
+
+        for (unsigned int i = 0; i < nn.numberOfLayers; i++) {
+
+            const Layer *L = &nn.layers[i];
+            const Matrix *W = &L->weights;
+            const Matrix *B = &L->biases;
+
+            int outputDim = W->rows;
+            fwrite(&outputDim, sizeof(int), 1, file);
+            //Anzahl der Weight-Werte
+            size_t weightCount = (size_t)(W->rows * W->cols);
+            fwrite(&weightCount, sizeof(size_t), 1, file);
+            //Anzahl der Bias-Werte
+            size_t biasCount = (size_t)(B->rows * B->cols);
+            fwrite(B->buffer, sizeof(MatrixType), biasCount, file);
+
+            inputDim = outputDim;
+        }
+
+        int zero = 0;
+        fwrite(&zero, sizeof(int), 1, file);
+
+        fclose(file);
+
 }
 
+
 void test_loadModelReturnsCorrectNumberOfLayers(void)
 {
     const char *path = "some__nn_test_file.info2";