diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 3ce4047..9cc0465 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -2,10 +2,62 @@
 
 ## Project structure
 
-
+```
+platform
+├── free_our_knowledge
+│   ├── __init__.py
+│   ├── settings
+│   ├── resources
+│   ├── urls.py
+│   └── wsgi.py
+├── docker
+│   └── Dockerfile
+│   └── docker-compose.yml
+│   └── entrypoint.sh
+├── manage.py
+└── requirements.txt
+```
 
 ## Getting Started
 
+
+### Development installation
+
+1. CLone the repository locally:
+
+```
+git clone git@github.com:FreeOurKnowledge/platform.git
+```
+
+2. Create a new virtual environment and activate it:
+
+```
+python3 -m venv fok_env
+source fok_env/bin/activate
+```
+
+3. Install all of the dependencies:
+
+```
+pip install -r requirements.txt
+```
+
+4. Generate the database tables:
+
+```
+python manage.py migrate --noinput
+```
+
+4. Start the project:
+
+```python
+  python manage.py runserver
+```
+
+If everything works the platform should be available on http://127.0.0.1:8000/.
+
+### Docker installation
+
 1. Build the development image. From the project root:
 
   sudo docker build . -f ./docker/Dockerfile -t fok_platform
@@ -19,3 +71,5 @@
 3. [Configure credentials]??
 
 4. Open a browser to http://localhost:8080/ to view the application (if using Chromebook, go to http://penguin.termina.linux.test:8080/)
+
+
diff --git a/apps/fok/models.py b/apps/fok/models.py
index ff0e677..3c82d24 100644
--- a/apps/fok/models.py
+++ b/apps/fok/models.py
@@ -125,8 +125,8 @@ class Meta:
 
     user = models.ForeignKey(get_user_model(), on_delete=models.SET_NULL, null=True, related_name='pledges')
     campaign = models.ForeignKey(Campaign, on_delete=models.SET_NULL, null=True, related_name='pledges')
-    implication = models.FloatField(verbose_name='Threshold')
-    author_position = models.ManyToManyField(EnabledAuthorPosition)
+    implication = models.FloatField(verbose_name='Threshold', blank=True, default=None)
+    author_position = models.ManyToManyField(EnabledAuthorPosition, blank=True, default=None)
     allow_public_name = models.BooleanField(default=False)
     created_at = models.DateTimeField(auto_now_add=True)
     updated_at = models.DateTimeField(auto_now=True)