If you have a truly killer idea and you lack the skills to make it happen yourself, you really have three major means to make it happen.
#1. Learn to make it yourself
Study. Learn to code. Learn to art. Learn to schedule. Make it happen. Maybe you can try recruiting some others to help you out as you go. You can try [posting on various game dev forums] for suggestions and help.
#2. Hire somebody to make it for you
Put up the money for the development, recruit some developers, and they can make it for you. As a general rule of thumb, you’ll have to consider that a full-time mid-level software engineer will cost around $10,000 per month of employment including things like office space, employment benefits, and taxes. This number will vary depending on where you’re located and such. If you go this route, you should be very careful about things like scope creep and the development schedule.
#3. Convince people with money that your game idea is worth making
Could be one person or a lot. It could be crowd funding. It’s going to be tough to convince the people out there to give you money for your game idea though - it’s not a very well-known process, and most of them will want to see something to demonstrate how or why the idea will work. If you can’t show them that, they probably won’t part with their hard-earned money. So that goes back to recruiting and building a demo of the game to make it happen… and that usually means leveraging your own money to pay for it.
But can’t I just sell the great idea to a publisher? Can’t I just be the “Idea Guy” and paid for it?
Publishers have their own people with decades of experience actually making games that come up with the ideas for games they wish to make. Everybody in game development, from the highest executive down to the freshly hired tester has their own ideas for games. Only a select few - the studio heads, the executive producers, etc. will ever be able to make that happen. If you want to be somebody like that, you either need to work your ass off to climb the corporate ladder, or you need to start your own studio and hire people to make your ideas happen.
That isn’t to say that publishers won’t take outside ideas - it does happen. But when you pitch an idea to a publisher, you aren’t pitching them the game idea - you’re pitching them your game studio’s ability to make the idea real. The team that did the Tony Hawk skateboard controller games originally pitched their idea to Activision by leveraging their team experience, a cool demo, and an actual skateboard and two Wii controllers duct taped to it. Publishers don’t buy ideas, they fund game development. They want to give money to qualified and experienced teams to build the game that was pitched.
Most people who enter the game industry do so because they already want to bring their ideas to the table. The vast majority of them want to make their games. You need to provide a compelling reason (like the money) for them to make your idea instead of theirs. Otherwise they’ve already got more going for them than you do - they have skills, they have experience, and they have ideas. Ideas are plentiful. Experienced and talented developers who can deliver are not.