First off, you're not supposed to tint your eyebrows - so there's that. The box literally says don't use this on your lashes/brows because it can blind you. Amazing. So I'm not brave enough to tint my lashes but I'm down with brows.
I used RefectoCil's Brow and Lash Tint in 4.1 (also avail on Amazon). It comes with a little plastic applicator that doesn't look like it would actually do anything but it ends up working very well.
You can buy a mixing plate or just use a piece of foil or a disposable plastic plate or something and you squirt some of your color on there and then mix in some of the developer (pictured above) which is basically the same thing as Hydrogen Peroxide just FYI. You're supposed to put a bit of the Eyebrow Tint on the plate and then eyeball adding the developer to it, which honestly feels a little scary when you're not a professional hair stylist but I just thinned out with like 10 drops and it was fine.
So then you use the little plastic applicator and paint it on your brows. There's a chart that says how long to leave it on. You get your "time" based on your natural brow color (I'm between a 6 and a 7) and the color you're going to dye it. So for me it was 10-20 minutes (which seems like kind of a large timeslot!) so I split the difference and did 15 minutes. If you're nervous I would err on the shorter timeframe as you can always go back and dye them again if they're too soft. I then used a makeup wipe to get it off. It does dye your skin too which you can clean up pretty easily with the makeup wipe but the skin under your brow will stay dyed til you take a shower (but it just looks like you filled it in with brow powder). People do who do it regularly do it about once a month.
Here you can see way the dye picks up on every hair - the ends of this brow are white and don't show up so it's nice that after dying them they DO show up.
So what's the verdict? I LOVE not having to fill in my brows everyday and feel much less like a redhead poser since I'm not rocking a brown eyebrow with red hair. That said, my red hair is a copper gold (warm) and this dye color was a cooler, pinker red so I'm just going to get my actual hair dye color (or a couple of shades deeper) and use that with the developer BUT, I'm so glad I went ahead and tried tinting my brows as it was super easy!