This tool is quite simple to use, it's for Chinese family relations. You start at the left with you then choose the relation to you and then the next person's relation to them until you end up with the desired relative. You can also select if they are older or younger than you as in some cases this may change the relative name. If there is an option, this tool will also give the formal and informal names. It will give the names with pinyin too. An example would be if you wanted to find out what your mother's (younger) brother is called in Chinese. You would have to select You - Mother - Younger brother. It would then tell you it'd be jiù jiù or jiù fù if it's formal Chinese relations.
If you want more instructions, you can also see our video What do you call relatives in Chinese? on Youtube.