Becoming a newbie and registering at this Mendix community site is a good start.
You will need to get added to the Team of the Mendix-app on sprintr.home.mendix.com. If not, call him and ask him to invite you. Only then you will be able to download the app's code and commit changes.
If you haven't done so already: download and install the Mendix Studio version. There are lots of versions. To know what version it is created in, on sprintr, click menu-option Team, then in revision see the last number, 10.12.1 in this case.
Learning paths: start with all 'Beginner' and 'Rapid' courses. Take the rapid certification test too, if you like. It's an easy test.
Making a change: open Mendix Studio, open the project, which will be in your list of project's once you are a teammember. It will download the project if it is not already downloaded.
Then you can make any change, run the app locally by pressing F5 or this button . Test your change, and once you are happy with the result, commit it (Alt-c, or menu Versioncontrol -> Commit). This only stores your changes in the version control on sprintr. To deploy it to your production-environment, you will need to 1) create a package and 2) deploy the package.
Welcome on board, and happy programming!
ok so i have a separate tab with "company apps" so looks like access is all there.. but how do I download one and see what is inside?