GIMP is free, if you google it, you'll get the website, just click download.
Making graphics is all a matter of trying and improving......I got better by just making stuff all the time, some of the first things I made were awful....
Many of those files are .gif files, so they're lots of different pictures put together so they play almost like a video. You can do that in a variety of ways, but when I do it, I use GIMP and do it frame by frame....It's quite time consuming, but once you know what you're doing, it gets easier.
The others just involve colour/brightness tools and other related colour palettes. The text is the classic icon small text followed by a larger more elegant word, it took me a long time to get the hang of that, but if you practice it enough and look at what other people are doing in fanart, it will help you get an idea of what you want the end result to look like...
Well, that's my advice, i'm sure other people would tell you to go about it differently, but that's how I did it, so there we are. =)