I am trying to add taint from Thaumcraft to every biome my world, how can I do this?

Based on the very sparse information you've given me, I would suggest a cluster decoration.

So what I am trying to do is cover everything with taint which is like vines or grass it's a thin layer, I know the ID of it, I have no idea what to put it the config file at all I have tried: forAllBiomes.addFlower("thaumcraft:taint_feature", 200) but it did nothing. I am really stuck any help would be awesome.

This is a place to report bugs, not ask questions. Ask in the discord channel linked on the wiki or seek help from someone that knows Thaumcraft.

I do not use Discord. What do I put in the script to make a specific plant to spawn in every biome?

The addFlower command doesn't do anything unless another mod uses, as detailed in the command description.

To cover everything with tainted soil, all you need to do is use the set command to set the topBlock field to tainted soil.

To cover the world with taint fiber, I would recommend simply using a cluster decoration with a very large count (so it generates nearly everywhere) and the soil block set to tainted soil.

To spawn monsters, you only need to use the addSpawn command.

See:
https://github.com/superckl/BiomeTweaker/wiki/Basic-Script-Commands#set
https://github.com/superckl/BiomeTweaker/wiki/Custom-Decorations
https://github.com/superckl/BiomeTweaker/wiki/Basic-Script-Commands#addspawn

If you are not sure where to even start, there is a (slightly out of date) Youtube video tutorial linked on the homepage of the wiki.

So where can I donate?

I don't think you quite understand what most of the commands are doing. To set the top block to tainted soil, all you need to do is all.set("topBlock", "thaumcraft:taint_soil"), assuming that is the correct resource location.

For the taint fiber, you need to find the resource location for taint fiber. I don't know it offhand, and then use that to make a cluster decoration. You seem to have not even attempted a cluster decoration.