how can I change the title of my forum?

Hi @Tomvictor!

To edit site title, you should go to admin control panel (available under the /admincp/ path of your site), its under the "Settings" -> "General".

To customize things like logo image, you should override the image files by uploading them to theme/static/misago and running python manage.py collecstatic. Likewise you can overrid templates by uploading them to theme/templates/misago.