Create a new raster layer below the text/shadow layer.
Use red from color swatch as fill and yellow #2 for outline/stroke. Outline width 3. Using Preset shapes tool, draw a rectangle behind letters (uncheck vector and uncheck anti-alias).
Create another raster layer below the red rectangle layer for a second border. Select the area around the red banner with Magic Wand (anti-alias unchecked, no feather) and then invert. Selections > Invert.
Enlarge the selection. Selections > Modify > Expand by 3 pixels.
On the new layer, below the red rectangle, flood fill the selection with green from the color swatches. Merge visible. If you want a transparent background on finished image, remember to hide visibility for raster background before merging layers.
Add a drop shadow for the banner. Use same settings as before except this time check the box that says 'Shadow on new layer'.
Optional: Add a 2nd drop shadow for the banner that is more of a green 'glow'. Make sure background banner is the active layer before adding the second shadow effect.
Effects > 3D Effects > Drop ShadowVertical: 0
Horiz: 0
Opacity: 50
Blur: 50
Color: Same green used for border.
Check 'Shadow on new layer'.
Use Crop tool to crop your canvas size down to include only the image area. Export as optimized GIF or PNG, with or without transparent background.
¡Happy Cinco de Mayo!
Kate