Though many feel that a wedding is the bride's day, it's really a celebration of the wedding couple. Many grooms don't know how to include themselves or how to even approach wedding planning. That doesn't mean that they should be left out. Not every groom will care about every detail but there should be some aspect of the planning that they want to have a say in. It's your job to find that aspect.
Part of the reason that many men pretend disinterest in their own wedding day is that they haven't grown up being targeted for wedding marketing. They don't know what to expect or what will be expected of them. Most brides are better prepared to begin wedding planning through mothers, sisters and friends than men will be. But don't let your groom's unfamiliarity or shyness with the unexpected get in the way. Let him know you value his opinion and want his input. That can go a long way in piquing his interest.
Some parts of the planning that might interest a groom are the honeymoon, your wedding night lingerie, the menu, your first dance song and the guest list. Some grooms care about the cake, the décor, the seating arrangements or the invitations. He should pick what he will wear and what his groomsmen will wear and have a say in many of the decisions, big or small.
If your groom is genuinely not interested in helping with the wedding planning, you, as the bride, should still insist, even if you know exactly what you want from your day. This is a celebration of the two of you as a couple and it should reflect both of you in it. Besides that, it's a good way to work on your communication, compatibility and decision-making. Many couples find wedding planning the most stressful part of their pre-marriage lives. How you handle that together as a couple can give you a few hints as to what your future will look like.
Every groom is different but every single one should care about some part of the wedding. As a couple, it's important that you plan the wedding together, even if the groom only helps a little. But you may have to go out of your way to get him interested and it may simply take you telling him that it's important to you. So though it may take some effort to find out what it is but it will be worth it.