Carefully place the condom with the opening between your lips, slightly unrolled, and then sexily slide it all the way onto your partner's penis. Another technique is for you to stroke your partner's penis to a full erection, lubricating it thoroughly, and then slip on the condom as you are finishing this manual stimulation. Regardless of how you put on the condom, doing so needn't be a damper at all, but can actually be quite exciting and erotic for you both. The two biggest factors for experiencing satisfying sex with condom use are adequate communication and sufficient lubrication. Clear and respectful communication increases the probability of consistent condom usage, thereby freeing you both from worrying about unwanted pregnancy and STDs.
Sexual lubricants can make condom use more enjoyable, which also reinforces continued condom usage.
I encourage you and your partner to experiment. Test out several different brands and styles of condoms to find ones that feel sexiest to you. Also experiment with how you can eroticize condom use during your lovemaking. The time and effort you put into this now will pay off in pleasure and intimacy dividends for a long time to come. In fact, one of the best parts of all this experimentation and dialogue is that you and your partner will enhance your overall level of intimacy and, along with it, your sexual connection and satisfaction.