This is basically what you do in the website:
Then you click on the link that says log into Instagram
After that you would be redirected to the website and they would give you 100 free insta-like credits
When you received the credits you can use it to get 3 different things. 1 positive comment, 2 likes on statuses, 3 more followers.
My advice for you is to not spend more than 11 credits for each follower. Also spend about 5-7 credits for each like and 3-4 credit for each positive comments.
After you spent all your credits you earn them again by liking other people's statuses, post positive comments, or following other people.
GOOD LUCK!