My advice below should all be taken with the understanding that as others have pointed out, you'll want to think seriously about whether this is really something you want to do. But assuming you've made up your mind, here are a few ideas to try to help you have fun and be safe-ish.
I see that you live in Michigan. The H you would find around there is probably so-called #4 heroin (it's common in the US midwest). #4 is nice because it's friendly to many different routes of administration (ROAs). So, my recommendation would be to snort it.
As for dosage, your tolerance is obviously going to bear on that a lot. But start smaller-than-small. The rule of thumb I follow when dealing with unfamiliar gear--and my tolerance is low to mid-range--is to chop up a bit that amounts to about the size of a match head, maybe even a tad less. That should translate to ~2 small, thin lines. If you're used to railing coke or pills, it will look like a ridiculously small amount. That's good!
Once you've snorted that, hang out for a while and see how it makes you feel. Onset for insufflation (snorting) of heroin is on the order of 10 mins or so. Having started with a safe dose, you'll probably want to go back for seconds. This time, roughly the same drill, though listen to your body.
And here's the part that I think is especially important. Others may disagree. What you want to avoid at this point is the temptation to keep going back to chase the initial high. Experimenting with dosage shouldn't be tied up with a long binge. If you can help it, make your first time all about finding a dosage that works for you. Going back for seconds is fine. Maybe more. But I've seen people get into trouble with new H when they didn't realize that it was creeping up on them... kept going back for more until suddenly they'd had too much.
Good luck. Be safe. If you have specific questions, feel free to PM me. I was in your shoes (with respect to heroin) about 2 years ago, so it's pretty fresh in my memory. But there are lots of folks with way more experience than me on BL, especially on the "other drugs" forum, so you might want to send questions there too/instead.