the list never ends: a bucket list

Open Gimp, click FILE --> Open, and choose what you want as your background.

Add a new TRANSPARENT layer by clicking on the thing that I circled in red.

Insert your text onto the background layer. Make sure your layers are in the same order as mine: TEXT, TRANSPARENT, BACKGROUND

Right click on the TEXT layer and click on ALPHA TO SELECTION. Your text should be the only thing selected.

Go up to SELECT --> GROW.

You can use whatever settings you want, but I have it at 5 px. This determines how big your shadow will be. For a bigger shadow, choose a higher number.

Now use the paint bucket and fill in the TRANSPARENT LAYER with whatever color you want your shadow to be.

Stay on the layer with the "shadow" and go to FILTERS --> BLUR --> GAUSSIAN BLUR

Use whatever settings you want. I have it at 3 px. This determines strong(?) your shadow will be. A higher number will give you a blurry (aka "lighter") edge/shadow.