如何以编程方式设置XAML中的行高？

I just need some quick help on syntax. I'm doing a WPF project and decided to try it out with Visual Basic. So, basically I'm trying to set the height of a row in a Grid. I'm not great at programming but with C# I managed somehow to figure it out, without remembering how. It actually looks like an animation because when clicking the button, the height of one row smoothly goes down to 0. I just need some quick help on syntax. I'm doin