Added first pipeline steps

Jenkinsfile

@@ -1,10 +1,40 @@
 pipeline {
     agent any 
+    parameters {
+        string(
+            defaultValue: 'marcinkostrzewski',
+            description: 'Kaggle username',
+            name: 'KAGGLE_USERNAME',
+            trim: false
+        )
+        password(
+            defaultValue: '',
+            description: 'Kaggle token taken from kaggle.json file, as described in https://github.com/Kaggle/kaggle-api#api-credentials',
+            name: 'KAGGLE_KEY'
+        )
+    }
+    environment {
+        KAGGLE_USERNAME="$params.KAGGLE_USERNAME"
+        KAGGLE_KEY="$params.KAGGLE_KEY"
+    }
     stages {
-        stage('Stage 1') {
+        stage('Install dependencies') {
             steps {
-                echo 'Hello world!' 
+                sh "pip install --user -r requirements.txt"
+            }
+        }
+        stage('Fetch and split dataset') {
+            steps {
+                script {
+                    withEnv(["KAGGLE_USERNAME=${params.KAGGLE_USERNAME}",
+                             "KAGGLE_KEY=${params.KAGGLE_KEY}" ]) {
+                        sh 'echo KAGGLE_USERNAME: $KAGGLE_USERNAME'
+                        sh 'kaggle datasets list'
+                    }
+                }
+                sh "chmod u+x ./download_dataset.sh"
+                sh "./download_dataset.sh"
             }
         }
     }
-}
+}