I have made some designs that I wanted to show you with GIMP.

The images are not to their dimensions here,are smaller.the real dimensions are much bigger,and if someone want to look at them must send me a p.m.

Thank You.

ENJOY THESE!

nice, you are very good with colors!

Love the first one best. How did you make it?

those are very nice =)

Thank You.I like the second one most.

You should know from other tutorials,if you love GIMP that the Layers are fundamental for a design.so I played with them,I used the difference clouds
filter,a gradient,and the sparks paintbrush tool.

I think to try to upload a Tutorial but it will not be the same,so the things you must remember are,for the sparks is,to brush to the background,that has overlayed a gradient and a second layer,that is the middle colorful tube to my design.the gradient must be at the top of the other two,to have the result of colorful sparkles.as you should know this brush is only yellow-orange.

For the tube you see in the middle,I used Difference clouds.
You can go to,Filters-render-difference clouds,and use X size 0,1 ,and Y size 16,0 for the values.you can play as you like.After I used the distorts filters and I applyed a gradient from the top,and then I overlayed it to the tube.

Good Luck!