tl;dr- Women's Day makes sense in some cultural contexts but not others. When appropriate, try to frame it as a celebration of societal progress. Be sure to avoid white knight syndrome and other forms of inadvertent sexism.
If you have a friend who's really struggling with money and worried about where their next meal'll come from, it can be kind to offer them some money. But if you have a friend who would otherwise seem to be doing well, just randomly offering them a bit of money to buy food could come off as rather awkward, if not outright offensive.
This issue is similar. If you know someone who's genuinely insecure about being a woman, then wishing them a Happy Women's Day or simply telling them about it can be an act of kindness. The more insecure they's feeling, the more appropriate a well-delivered comment could be.
But if a woman feels that she's an empowered, respected individual, then offering her a reminder that she's
stringer then men and capable of way lot then any men can think
will sound weird, like offering a fiscally stable friend money. If this is hard to imagine, consider someone telling you that it's Men's Day and that they appreciate you for being a man; weird, right?
The important thing would seem to be ensuring that you're delivering these comments to people who'll appreciate them. This is, you probably shouldn't just randomly message every woman you know; that'd probably come off as weird overall. Instead, if you have a female friend who you know feels unappreciated because she's a woman, then you might mention the holiday to her in conversation, telling her that you're happy to see the public gesture.
And to warn ya, it sounds like you might have a touch of White Knight Syndrome. You'll probably want to reflect on that a bit before messaging anyone.
Finally, if/when you do message someone, it's probably best to point out Woman's Day as a societal showing of respect/equality, rather than as a personal gesture on your part. If you have a bit of White Knight Syndrome, you may be hoping to score some personal points today, but if you really care about folks, that's probably not the best idea. If a woman's feeling insecure, ideally she'd feel appreciated by society, not just by you personally.
Consider who'll appreciate a Happy Women's Day rather than just saying it to everyone.
The holiday's about society appreciating women, not you. Completely remove yourself from the picture, and don't try to use today as a chance to score points.
Be careful to avoid accidentally implying anything bad about women, even implicitly through your actions.
You may want to reflect on your own views of women a bit, as the original wording of the question sounded a bit off.
RE: Cultural notes
Just thinking about it a bit, the culture that you're from would seem relevant.
In the part of the world where I'm from, there's simply nothing wrong with being a woman. Telling a woman that she's appreciated for being a woman would pretty much be the same as telling a man that he's appreciated for being a man; this is, it'd seem weird and a touch sexist.
But, I appreciate that cultures vary significantly around the world. And, in some parts of the world, women are subtly marginalized; in other parts of the world, women are blatantly marginalized. So, Women's Day would seem to make a lot more sense elsewhere.
So, I suppose that a correct handling of this issue would vary significantly by culture.
RE: Framing Women's Day
In the above answer, I'd suggested that words of encouragement would be appropriately delivered to those who're feeling insecure. This framing seems like an objective way to consider the situation, but it's not the right framing for external discussion.
When trying to actually make people feel better, it'd seem more effective to frame Women's Day as a cultural celebration that everyone's doing. I guess that calling it "International Women's Day" was actually clever, in that it helps to reinforce this framing. This framing makes it sound more like something everyone's doing, rather than a specific showing of support, taking that awkwardness out.