How do you make that happen?
Do your research.
Search for the conference that will have a few agents attending that represent your genre. Once you make your decision on which one to go to, register and pay your money and then watch the calendar for the BIG day to arrive. While you wait, you will need to write a log line, a hook and a pitch. You will need to practice your elevator pitch (30 second blurb--or about 25 words or less--on what your novel is about). It is harder than you think. You need to cram 80,000 words of your novel into an interesting sentence or two that will have your agent or editor drooling. You want them to ask for your novel immediately.
A great pitch example by J.K. Rowling for Harry Potter and the Sorcerer's Stone is:
A boy wizard begins training and must battle for his life with the Dark Lord who murdered his parents.
Once you have your pitch ready, it will be a piece of cake... unless, you are attending a Pitchfest. A Pitchfest means there are many agents in attendance (about 60-90 agents), waiting for you in one room (sometimes two or three rooms) and you need to pitch to these agents one at a time. This is stressful. I attended Thrillerfest in New York City in July 2016 and the Pitchfest experience was unbelievable! If you want to know about more details regarding my experience, go to the Ascribe Writers Website HERE and read the guest blog I did about that, called "World's Largest Opportunity to Pitch to Top Literary Agents". It is well worth your time, I promise. It might scare you BUT it is so worth it. It will be the best way to approach an agent with your novel. Be brave and just do it. Tell me all about it when afterwards. I'm anxious to hear how it goes for you. Good luck