https://www.modcoderpack.com/
https://www.eclipse.org/downloads/
You need those two. Then its just to fix the build path, and start coding. You can find tutorials on youtube. Your first client probably won't be good but keep trying and dont copy code without knowing what it means.
this clickgui is kinda good i guess:
https://******.com/DarkStorm652/Minecraft-GUI-API
https://slick.ninjacave.com/