I have an animated gif and wanted to use it in the animation but I'm not sure how.
Blender does not support the gif format.
You would need some other software to convert your gifs to a format that blender understands to be able to import them.
For a list of supported formats see here
There is this plugin: https://github.com/doakey3/bligify
I was not able to get it to work, but maybe it would work for others.
You can convert your animated gif into a video, or start with video in the first place, and use that as a texture.
It can be a little problematic if you wanted some transparency, in which case you also need to make a video of the mask you want to animate.