FIRST KNOW THAT YOU HAVE TO BE LEVEL 10 AND UP
*this guide is also very basic, i go into how to add a gif to an image, not how to make gifs*
use this guide for the backgrounds for your steam first before following this guide. this is pretty much a continuation if you want to add a gif to your artwork.
these are the basics, not anything too advanced

for this example i will use this background:


next step would be to download gimp (pretty much photoshop but i aint rich man) and the add-ons to edit gifs:
-gimp: http://www.gimp.org/downloads/
-animation add-on: http://chiselapp.com/user/saulgoode/repository/script-fu/artifact/f81f476d508010f1dde9190a3ff47afc602425fc

to install the add-on follow: https://en.wikibooks.org/wiki/GIMP/Installing_Plugins
once these have been installed you will also need a transparent gif that you can steal off of www.google.com
i will be using this gif:

open gimp and open your transparent gif in it
it should look like this when opened:


if the add-on was installed correctly, once you go to filters at the top bar and then animation, there should be an option that says settings:


open settings and a window titled "script-fu: settings" should appear.
in the delay box, enter -1
and in the mode:: box, switch the option to clear and press ok.

your layers window(if not opened go to windows at the top bar,dockable dialogs, and then layers)
should say only frame 28(number of frames down, in my case 28 is the highest frame),27, ...background and etc. instead of 70ms or how fast the frames are on your gif.
image reference:

when the last step is completed export your file as a gif. (name is nameuwant.gif)
-clicking export at the first box will cause a second box to appear saying "export image as gif"
at this box check the small box that says as animation and then press export.
image reference:

if you're curious as to what you just did to your gif it looks like this when played:

if this step wasn't done your gif will not turn out correctly when placed on a static image

open the image that you downloaded first and then add your revised gif to it
you will most likely have to adjust your gif to where you want it to be placed
to do this you will have to link all of your frames together, leaving out the downloaded image.
hold shift and click on the box that appears next to the eye in your layer box. (holding shift is just a shortcut so that you don't have to click them all individually)
once a chain has appeared next to all the eyes, scroll down the layer box and click on the chain where your downloaded image is so you don't move it with the other frames of the gif
use the move tool (four arrows in the tool box or press m) to drag the gif where you want it and afterwards to unlink all the frames hold shift and click on one of boxes twice and then unlink the remaining frame.

*if you have to resize your gif you can link all the frames together besides the static image (like in the last step) and then use the resize tool in the toolbox to make it what size you want.

the next step is the most tedious out of the steps, unless you're able to find a way to do it quickly.
if you have a gif with very few frames then you are in luck because for this step you will have to merge the layers of each frame to a duplicate of your image
*continuously repeat this step until all layers are completed
1. in the layer box, click on your image and then click on the the double box icon below it:

*for a more efficient way of doing this, once it is duplicated, drag the copy of the image above each frame of the gif (and then do what # 2 says every frame merged) for example:

2. click on the layer of a gif above the duplicated image and then go to the main window of gimp and select the layers tab and click on "merge down"

you will have to do this for each frame, duplicate the image, merge down the frame, duplicate merge, duplicate merge, etc. tl;dr: duplicate stock image for each frame and merge each frame to it's own image
if this step has been done correctly, your layer box will look something like this:

all frames should look like they have a background behind them on the layer box preview
after that is done your gif is pretty much finished. to check if you did it correct go to filters, animation, and then playback. there should be no glitches or anything, it should be just your gif over the background.

save your results the same way you saved when removing the frame disposal method (rename your gif so its yourgifname.gif) if it brings up "the image you are trying to save as a gif contains layers which extend beyond the actual borders of the image." just select crop and it should be fine.
when you get to the point where a window like the image below appears make sure the "as animation" is checked and then export


the gif i made was a little too big for guides (2 mb max) but it should be something like this:

if you insist on making your gif work you can somewhat shorten it on this site: http://ezgif.com/optimize

upload your finished gif here: http://gtm.steamproxy.vip/sharedfiles/edititem/767/3/ (artwork)
when completed set the image to the spot it should be in your artwork showcase.

i just made this for the heck of it so if you find flaws help a boi out
if you can make gifs yourself then you probably wouldn't need this tutorial anyways, its for people who live off of google gifs
remember to unlink!
ignore the white lines, those are all a part of transparent gifs that you rip off of google, white lines probably wouldn't be a problem if you cropped the gif yourself
add me up if u want but i will not help make a gif or help with troubles as of now, it isn't my thing and i probably won't do a good job at it

thank you all for 5 stars <3 2/27/16