Step 1: Parent Create Child's Church Account (recommended)
Parent go to https://www.churchofjesuschrist.org/ (phone or computer)
Click the person icon in the top right corner of the page
Click Sign In
Log into parents account
Click the profile icon in the top right corner of the page
Click "Account Settings"
On mobile, expand menu by clicking blue menu button in top left corner
Click "Children Accounts"
Click "Create Account" next to the child's name
Enter the desired username and password
Click the checkbox: "User parent's recovery email"
Finish creating account
Sign out
Step 2: Log into FamilySearch
Click "Sign In"
Click "Sign In with Church Account"
Enter your new Church Account username and password
Click Verify
Click "Family Tree" > "Tree"