The Bible is about religious and moral issues, and not about money at all, let alone charitable giving.
It is a common idea that the Bible has only to do with so-called religious matters, e.g., church attendance, individual conversion, and personal piety. But this is a misunderstanding, probably derived more from cultural hearsay than from careful reading of the Bible itself. Really, it would be fairer to say that the Bible is about everything. The Bible covers the waterfront of human life because the gospel of God’s redemption covers the waterfront of human life. In the words of Scripture, God is reconciling all things to himself through Christ (Colossians 1:20). “All things” certainly includes money and material possessions, so it is no surprise to find that the Bible speaks plainly and frequently about these things. There are philosophies that separate reality into “spiritual” and “material” spheres, but Christianity is not one of them. In the Bible, all of life (including the use of money) is spiritual because God is involved in it. When we take the time to read the Bible carefully, we find that it has much more to say to us than we may have realized, not least of all about our giving. Start by reading these key Bible verses on money and stewardship.
The Bible commands us to give in secret, so we shouldn’t be talking about this.
Jesus’ admonition to “not let your left hand know what your right hand is doing” is not a prohibition from public giving of all sorts. In Matthew 6:1-4, Jesus is warning against doing things for the purpose of impressing others, but this does not mean that everything about giving must be strictly private. As sinners reconciled to God, David, Barnabas and the Macedonians inspired others with their public generosity, and Paul publicly expresses his gratitude for the generous giving of his congregations (see 1 Chronicles 29, Acts 4:32-37, 2 Corinthians 8:1-5, 9:1-5; Philippians 4:14-18). In fact, because of the dangers of love of money, consulting openly with other believers about our stewardship practices can be very wise, even necessary. It may also inspire others to give, and give them opportunity to praise God for our generosity (2 Corinthians 9:11). If our motivation is to impress others, it is better not to mention it. But if we need help staying faithful, or if we can encourage others, it may be appropriate to share about our giving.