Create a new canvas.
W = 5 inches
H = 3.5 inches
res = 300
You can switch the width and height if you are making your postcard in portrait style.
Use your text tool to add text to your image. Don't forget to change the font, font size, color and use the warp text
Use Layer Styles to make your text POP.
Double click on the layer you want to add your layer stlye to. Or - Layer - Layer Style
Choose the style you want and play with the options it provides