First thing to do is to join a writer's critique group, if for no other reason than to get a non-family member to read and critique strong points, weak points, etc.
Go to the library, and in the magazine section, look at Writer's Digest, The Writer, any of those and see what agents are mentioned. There is also an entire book issued each year--The Writer's Guide to Literary Agents. On the computer google "Editors and Preditors" and it will bring up thousands of agents and publishing houses. Find an agent who specializes in the genre your daughter writes.
Next option, google "writer's conferences" and see what will be anywhere near you. Each specialty genre (mystery, sci/fi, romance, etc) have conferences in almost every state. They have sessions on how to submit, what agents want to see, etc. Also, they have agents and editors who will read the manuscript and give advice.
What state does your daughter live in and what genre does she write?