Looking for a Literary Agent

I have a wonderful story that I just feel a great need to share. The only writings I have had published has been some of my poetry. I have searched and read the books on how to get published, but most publishing companies require an agent to submit your manuscript. All these publishing how to books do not get into how to get a literary agent. I found sites that if you pay for a service they will help you find an agent but I am not sure if these sites actually work. So I am feeling very frustrated. If you are a published author I would greatly appreciate any advise you can give. I truly desire to get my story out there. It is a children’s story but I believe adults will enjoy it as well. I look forward to learning from you what you can share in getting this done. Thank you. Julie S.