Documentation on using GeoServer can be found on their website at the following link:
https://docs.geoserver.org/
Any support issues you can take a look at their forum
http://geoserver.org/comm/
Any issues regarding the installation you can contact us directly or leave a comment below and we will assist as much as we can.
Disclaimer: GeoServer is licensed under GNU General Public license. No warrantee of any kind, express or implied, is included with this software. Use at your risk, responsibility for damages (if any) to anyone resulting from the use of this software rest entirely with the user. The author is not responsible for any damage that its use could cause.