I do.  This is all very confusing to me and I want to ensure that I do this right.
You can take your time doing this.  After you start a Child Disability Report you can always use your re-entry number to return to working on the report online.
Is there a way to find all the necessary information in order to apply for disability for a child?
You will need to complete and Application for Supplemental Security Income and a Child Disability Report.  The report collects information about the child's disabling condition and how it affects his/her ability to function.