The gutter system on your house is designed to ensure that rain water is collected and carried away from the house. This ensures that you are protected from lots of issues and problems that are caused by water pooling around the house.
Gutters are installed by professionals although some people prefer to do it on their own. However, it is wise to hire the services of professionals because they have expertise and knowledge that is required during installation. If you do it on your own, you might end up causing more harm than good to the roof which will not serve the purpose that it is intended to do.
There are lots of home improvement professionals, both available online and offline.