Lower Alpha on Texture2D

I can not for the life of me work out how to do this and all the answers here haven’t seemed to help.

I want to draw some 2D textures onto my GUI. I want them to be a certain colour and width and I also want to change the alpha of the textures to be at about 60% (so they are semi transparent).

I’m assuming I will have to create my own Texture2D class or object and then change the alpha this way? I’ve tried creating a Texture2D in photoshop and importing the asset into unity but there doesn’t seem to be a way to change the alpha this way.

So should I instead somehow try and create my own texture2D, create a custom colour, fill the texture with the color and then change the alpha?

Decided instead of using an imported image to create an empty texture, then a new colour and set the pixel colour for each individual colour. It’s working fine the code I used for this is below:

selectbox = new Texture2D(5,5);
		selectcolor = new Color(1,0,0,0.5f);
		for (int i = 0; i < 5; i++) {
			for(int j = 0; j < 5; j++) {
				selectbox.SetPixel(i,j,selectcolor);
			}
		}
		selectbox.Apply();