Presumably you are using
SpriteBatch is only capable of drawing rectangles. You need to go lower-level.
What you are looking for is how to draw 2D primitives.
I'll leave it as an exercise to search the web for an appropriate tutorial. But you will probably find yourself at least using the
BasicEffect class and the
In fact, you probably want to look up how to use the method
GraphicsDevice.DrawUserPrimitives<VertexPositionTexture>(). That is an ideal place to start.
I'm going to assume that you are good enough at coding to figure out how to modify the contents of your vertex array each frame in order to animate it. If you need a starting point, look up "lerping" ("linear interpolation"). Particularly the
Vector3.Lerp method. MSDN is your friend.