Hi welcome to the Monastery. We just saw your buddy doing the Bitcoin app a few months ago! Nice to see y'all are keeping up with the new stuff ;-)

I suggest to read the documentation for JSON as well as about Perl data structures (perldsc) so you can access hash elements at will.

Also, I suggest getting handy with jq so you can parse random JSON on the commandline. For instance, you could extend your command shown to:

# perl libra_test.pl | jq .balance
[download]

Hope this helps!