Updated instructions to start docker container

00_GettingStarted/README.md

@@ -56,7 +56,7 @@ A `Docker image` is a **snapshot of an application or system** that has been pac
 
 In `Introduction to Robotics` we will provide you a `Docker image` that is a snapshot of an **Ubunutu operating system** with the **Robot Operating System (ROS)** installed and all the necessary additional libraries that will be necessary for this course.
 
-In the following section you will find information on how to install `Docker` and how to start a running `Docker container` as an instance of the `Docker image` we provided for this course.
+In the following sections you will find information on how to install `Docker` and how to start a running `Docker container` as an instance of the `Docker image` we provided for this course.
 
 ### Installing Docker
 
@@ -69,7 +69,7 @@ After successfull installation, **open** `Docker Desktop`. The GUI should open a
 ### Starting a Container to work with ROS
 To make sure you can all start with the same working `ROS` environment we use a predefined *image* and *compose* file. Both are stored in this repository at [00_GettingStarted/docker/i2r/](docker/i2r/).
 
-Following the instructions to download the repository to your local machine and start the group of containers:
+Follow the instructions to download the repository to your local machine and start the group of containers:
 
 1. Create a folder named ***i2r*** for the contents of the `Introduction to Robotics` course.
 2. Open this folder in `VS Code` by either starting `VS Code` from Terminal or by using the GUI.
@@ -100,12 +100,33 @@ Following the instructions to download the repository to your local machine and
     ```bash
     docker compose up
     ```
+    This command will download the needed images and start two containers. One container named ***i2r-ros-1*** which contains a snapshot of an Ubuntu OS with ROS and additional packages installed. The second container is an auxiliary container named ***i2r-gui-1*** that will be used to inspect graphical user interfaces of applications started in the i2r-ros-1 container. 
+    
+    The terminal output will look the following:
+
+    ![Terminal Output for *docker compose up*](images/docker_compose_up_terminal.png)
+
 7. In the `Docker Desktop` GUI go to the *Containers* tab. You should see now, that there are two containers launched under the group name *i2r*.
-    - Another option to inspect the containers is using the terminal.
+
+    ![Docker Desktop GUI with group of containers running](images/docker_group_running.png)*`Docker Desktop` GUI: Inside the Containers tab you should find the started group of containers.* 
+    - Another option to inspect the containers is using the terminal. (Note: If you are still in the terimal you executed the *docker compose up*, make sure to start a new terminl, but let the old terminal running.)
         ```bash
-        docker container ls --all
+        docker ps --all
         ```
-
+        The terminal output will look the following:
+        ![Terminal output for *docker ps --all*](images/docker_ps_all_terminal.png)
+        There will be information like ID of the container, name of the image the container was build from etc.
+8. To connect to the ***i2r-ros-1*** container, the container we will use to work with `ROS`, execute the following command from terminal:
+    ```bash
+    docker exec -it i2r-ros-1 bash
+    ```
+    <!-- blank line -->
+    <figure class="video_container">
+    <video controls="true" allowfullscreen="true" poster="images/docker_exec_rosContainer.png">
+        <source src="images/docker_exec_rosContainer_video.webm" type="video/webm">
+    </video>
+    </figure>
+    <!-- blank line -->
 
 
 ## In case of problems