U have to be in these groups. Badges will be rewarded automatically just as leaderboard badges.
So , how can I join these groups ? Please tell me . And thank you so much for replying my questions 
Ask a member already in a group. U can join via invitation or link
Walaykom Salam. The best approach is to visit the profile of a user with a public account and ask him to invite you to one of the custom leaderboards he’s part of.