make sure u dissolve it thoroughly in water then just shoot it up your butt, same way you'd plug anything. i would filter it before drawing it up the syringe, because black tar heroin sometimes has microorganisms in it due to the glucose content. could cause a butthole infection haha. but you should know that heroin has poor rectal bioavailability. it's slightly higher than its oral bioavailability, which is extremely low (1-5% in most cases). if i were you, i would smoke it. i'm assuming you don't want to inject it. inhaled heroin's bioavailability verges on 100%, but a lot of the heroin is destroyed by heat. the trick is holding the flame far away from the foil. contrary to popular belief, you dont want a huge plume of vapor. if you get a giant plume, it's mostly smoke, not vapor. in that case, what you're inhaling is destroyed heroin and adulterants. you want to hold the flame just far enough that you get a small but substantial stream of vapor. it will taste very very vinegary. you'll know that you're holding the flame too close because it won't be as vinegary as normal, and it will burn your throat much worse (although no matter how you do it, it burns. it's acidic as fuck). make sure you hold in the vapor as long as possible. when you exhale, you won't see any visible vapor come out. this means you did it right. if you have a low tolerance you should feel pretty loaded after a couple hits. the good thing about smoking heroin is that it's pretty much impossible to OD. you will know that you've taken too much because you won't be able to lift the foil and you'll be throwing up and nodding out super hard. this is the point at which, obviously, you should stop. even if you weren't planning on stopping, you'll be too nauseous for the thought of more black to even be appetizing. so it's kind of self limiting. even though the rectal BA is very low, it's still possible to plug too much and overdose. and once you start feeling that you've taken too much, it's already too late. it's the same level of danger as consuming any opiate orally, nasally, or intravenously. once you put it in, you can't take it out. the advantage to injecting heroin is that you can inject a portion of the syringe. you don't have to plunge it all at once. this way, you can inject a bit, wait 5 minutes, then inject more. it's actually a lot safer than it's stigmatized to be. for plugging this is pretty difficult, because you have to wait at least 20 minutes to notice any effect at all. it's even possible for the full effect to hit you after as long as an hour, so you can't really attempt trial and error with this method unless you wanna drag it out for several hours which defeats the recreational value in my eyes.