How do I add a color layer + put text on top

[enginestar]

I have an image.
I want to put another layer on top - say white or black.
On top of this layer, I want to put text.

What's the best way of doing this?

I thought it would be simple.
But I'm struggling.
I've started by created a new image. Then color the background. Then copy and past onto the image. And then add text on top.

I seem to be going wrong. I'm struggling to resize the layer or cut a bottom or top part off.

Hoping someone can point me in the right direction.

Thanks.