A lot of security relevant bugfixes have been done. So because of this we recommend you to update to this version soon. There is also a new language "Estonian" available.
We recommend you to read our announcements for version 4.2 if you have not done before.
A full list of all new features and bugfixes can be found in our issue tracker for version 4.2 and 4.2.10!
If you are new to Admidio and want to install it on your webpage than the following wikipage could help: Install Admidio
The following wiki pages maybe interesting on an Update: Update Admidio