ACP certification is basically designed to provide understanding of Agile concepts at basic level. So the eligibility criteria is set as below:
2000 hours of experience in working on any project team that may or may not follow Agile.
1500 hours of experience in working on project team following Agile
21 hours of training on Agile Project management concepts
So here are your steps towards ACP Exam preparation:
1.Gain experience as prescribed above.
2.Register for membership with PMI
3.Focus on topics defined in study guide
4.Read the official reference books
5.Enroll for the workshop/training to completed 21 contact hours on agile topics. Check with PMI chapter near you or any education provider registered with PMI
6.Join the official group in LinkedIn
7. Once you are ready take Exam.
For more details download the handbook
Good Luck!