how to use indigo powder with henna - #25096

I am really curious about how to use indigo powder with henna because I recently tried dyeing my hair at home, and it didn't go as planned! I have dark brown hair naturally, but I wanted to go for that rich black color. When I mixed the henna, it looked great at first, but then it turned out way too reddish for my liking. I read somewhere that using indigo powder with henna can help achieve that nice black hue. I tried to mix them together but ended up with a weird consistency — like too thick or something. Honestly, I don’t even know exactly how to use indigo powder with henna. Do you mix them together, or apply them separately? Anyone had success with this? I was also wondering if I need to do anything special to prep my hair or if there’s a specific sequence to it? Like, is there a waiting period or something important to know? I'm just really looking for some guidance here because I don’t wanna mess it up again. Thanks in advance for any help!