Stretch out stimulation and sex and keep yourself on the edge of having an orgasm for a while. When you feel like you want to orgasm, move stimulation somewhere else for a bit before restarting. See how long you can go before you have to orgasm. Then push out like you do like you want to pee while you orgasm.
Not all women enjoy gushing, and not all women even gush. Don't think that you are missing anything if you do not gush. Enjoy sex for what it does for you, for how it makes you feel and for the intimacy with your partner. Do not chase goals like this. It will just make you miss out on the wonderful experience of sex, and make you feel defective and frustrated..
Many women will also become more orgasmic and develop the ability to gush as they mature. Often in their late 20's.
Best of luck!