need help making custom weapons

How do i make them?I have no knowlage of scripts but i used doom builder 2 in the past if u make them with that although i think its only a level builder.Please tell me how to make them i want to make a shoop da whoop gun for doom or some other gun.Can someone tell me how to get a custom image in the gun and the damage and all that.I HAVE NO IDEA HOW TO MAKE THEM PLEASE HELP ME!!!I'm a doom newbie.

Did you read up on this already?

http://zdoom.org/wiki/DECORATE

There's also a tutorial on drawing the weapon here .

Good luck!