How do i use a protein filler before coloring my hair?

i recently tried to go bleach blonde,big mistake,anyways im going dark so i got my color but i know that using a filler will help me achieve the color i want so when do i put the filler on,or do i mix it with the color and apply all at once??

I would check with the instructions because each is a little different with processing times, etc. But a generally, you put on the filler, let it set, then color over it. The filler will "fill in" the overprocessed areas that the bleach left behind so that you can have even coverage with your darker color. Make sure you get the correct color filler for the base tone of your hair. Also, if it is a protein base, you may need to rinse it out before color - protein can break your hair off if left on too long. Good luck!

read the instructions.......