Try something like this for a basic node:

$node = {
    name => 'foo',
    children => [],
};
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This particular node has the name "foo" and no children. Adding a child to it, can be done like this:

push @{$parent->{children}}, $child;
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where both parent and child are nodes set up as above.

Use Data::Dumper (/me looks sideways to demerphq for his reaction) to see what's in your tree, for experimentation.

Of course you're free to add more fields to a node, to hold the actual data.