Question I can't use Stardew valley NuGet package

[Seon_0]

I download it, and it says it can't find things like StardewModdingAPI, Microsoft.Xna.Framework
How can I fix this problem?? Because of it, I can't use 'using'

 

[BlaDe]

Have you installed smapi?

 

[Seon_0]

Have you installed smapi?

I just forgot SMAPI thx!!!!!!!!!!