Heather Corinna replies:
I'm 21 years old I've been sexually active since I can remember, and never was interested in getting or giving a blowjob. But now, I want to but don't know how to give oral sex in a way I know he will ejaculate. So I just open my mouth and then what?
Plenty of men will reach orgasm and ejaculate with oral sex, though many of those men won't do so every time. Some men will rarely reach orgasm that way, and some men never have and might not ever, despite the fact that what their partners have done has felt good, has been exactly what they wanted, and no one was doing anything "wrong."
So, if in order to engage in fellatio, you feel like you have to have an orgasm or ejaculation (which are separate things, to: men won't always ejaculate when they orgasm) happen, then you're going to need to reconsider how you're thinking about this, since that's not something you can control, nor can your partner. If giving oral sex is all about reaching a certain destination for you (or him) rather than enjoying the ride, not only are you less likely to reach that destination, you're a lot less likely for both of you to enjoy yourselves the whole way there.
As to the how: people vary very widely in what they like, men included, oral sex included. In general, what male-receptive oral sex -- fellatio, or a "blowjob" -- is is simply stimulation to the penis and surrounding areas (like the testes) with a person's mouth, lips and tongue. That can be sucking on the penis, licking, rubbing lips over it, or combining any or all of those things. It's also common to engage the hands during fellatio, as well, be those your hands or your partner's hands, for extra stimulation of the base of the penis, testes, anus, buttocks, hips or thighs.
But what feels amazing to one person may be totally ho-hum to someone else, so the only way to find out what your partner likes and gets off on is to do two things: communicate and experiment. That means you try something, you ask him how it feels (i.e., "Do you like this? Want me to do it more like this?"). Or, he lets you in on something he knows feels good, and then you try it and see, and you both keep experimenting and communicating like this over time. Your partner may like, for instance, to have you lick or suck under the head of his penis, or that may feel too ticklish for him and he may prefer more attention is paid to his shaft. He might not like being sucked in a way that's very intense, but another partner of yours down the road may think that's heaven. One partner may like more hands than mouth, another may like the opposite, and what any given partner likes may even differ some from day to day. The only way to find all of this out is to talk about it together, try and few things, see how it goes, and talk some more.
Too, this isn't just about him, it's also going to be about what feels good to you. Your mouth is a sensory organ, so in a lot of ways, fellatio -- when it's what you want to be doing -- should feel good in the same way that kissing feels good, and should be something where you can go with the flow in that same way. There may also be things he enjoys with oral sex but which either hurt your jaw or throat, or are things you can't sustain for ten minutes: that's okay. Like any kind of partnered sex, this is all about finding middle ground with what works for both of you and feels good for both of you.
None of this should be surprising if you're already sexually active in other ways, because the same sorts of experimentation and communication should be going on with intercourse, receptive oral sex for you, manual sex, even just making out. When people say that good sex takes practice, this is what they're talking about. People who have satisfying sex lives together do not tend to have them in an environment of silence, nor one that's about performance or about product, not process. Great sex is all about communication and enjoying shared, unique personal expression.
Just a reminder? Oral sex does pose risks of sexually transmitted infections, so if you and yours have not been sexually monogamous for at least six months and have not also had at least one full STI screening (both of you) with negative results before oral sex, you'll want to protect your health by using condoms for oral sex until those two conditions are in place.
Here's some extra information for you, including a guided tour of your partner's sexual anatomy, which is something else, paired with that experimentation and communication, which can help you get a good idea of what's what and what you might want to try.