hwo to apply a glass effect as a background of my vstack ?

To apply a glass effect as a background to your VStack in a SwiftUI app, you can use the Liquid Glass effect introduced in the WWDC sessions. Here's a general approach based on the information from the sessions:

Create a Glass Effect Container: Use a glass effect container to group your elements. This ensures that the glass effect is applied consistently across the elements and improves performance by sharing the sampling region.
Apply the Glass Effect: Use the Glass Effect ID modifier to apply the glass effect to your VStack. This involves declaring a local namespace and associating it with the glass effect elements.
Use the Liquid Glass Material: The Liquid Glass material reflects and refracts light, picking color from nearby content. It adapts to its surroundings, ensuring clarity and legibility.

For a detailed example, you can refer to the session Build a SwiftUI app with the new design (17:57) where the Liquid Glass effects are discussed. This session provides insights into how to implement and use the Liquid Glass effect in your SwiftUI app.