What kind of knowledge do you need to start a company?

Surely someone must have asked this before, but I couldn't find it, so here goes.

I have a degree in computer science. I'm a software developer. But I love the idea of getting into business. But I have no idea how.

Let alone the fact that you obviously need an idea; that goes without saying. Let's assume I had one. Let's assume it's great.

What kind of knowledge do I need to start a business? Economics? Management? Marketing? Law? These all seem crucial, and yet many entrepreneurs only have degrees in their field, e.g. computer science.

How do you build up the knowledge base of what it takes to create and run a company?

The tl;dr :

Learning how to ride a bike requires first hand experience - and a couple of falls. Books / simulations won't do it. Same idea applies to startups. Whether you're willing to accept the risks inherent when grabbing the handlebars for the first time + how you react after the first couple of falls will uncover if it is something you want to pursue or run away from.

That said, here are some points. Others may not agree - that's their right.

I love the idea of getting into business. But I have no idea how.

Okay, but at one time you had no idea how to code, correct? You took the initiative, picked up a book, met others who code, and built your talent.

Same thing applies here. You need to read books about startups (read some of the posts here - a lot of good suggestions [try steven blank, eric ries, etc]. Meet with other people doing startups (meetup.com, perhaps?) Do some work to determine whether your idea is truly what your intended market is (again, research will show what methodologies to use). Modify / change as data dictates.

What kind of knowledge do I need to start a business?

Knowledge isn't as important as the ability to learn / interpret the results of your actions. Sure, some intellectual baseline is needed, but everything you believe is correct - idea is great, customers will pay, will only cost me x hours / y dollars - is only a guess. And likely not to survive first contact with your intended customer base.

How do you build up the knowledge base of what it takes to create and run a company?

Universities were built on the notion that studying / deconstructing past successes helps prepare a roadmap for future success. Many today state that startups are an entirely different animal with their own set of conditions. Search out both sides, understand their positions, and form your own opinion. Then you're on your way towards building a knowledge base upon which you can test your assumptions.

I'm in the similar situation as you (software developer) with some good ideas..
Even though I started a company with my friend a time ago it turned out it still does not mean anything when I started to search for some answers to similar questions as you. And soon I realized that starting a company with an idea is one thing and the working business is really another one.

So first forget about starting a company when you've got only an idea. You actually need a working business model prior to starting a company.

I would recommend, as someone already mentioned above, to check The Lean Startup book by Eric Ries. But it still lacks some methodology or guide to make any measurable progress.
Thus I would much more recommend the book by Ash Maurya: Running Lean and his Lean Stack methodology which is really helpful to follow the principles of a lean startup and also offers a step-by-step guide for creating viable business from any idea.

One thing always strikes me when I got any new idea:
The idea is nothing (cheap), execution is everything (expensive)!

So keep that in mind and follow your path ;)

Knowledge/ Research will depend on the kind of Business you are looking for.. Here is the list of Knowledge/ Research required to start a company..

General Knowledge/ Research Required:

• "DEMAND & SUPPLY GAP"
• Proper Market Research
• Analysis of the PLAYER's in those sector
• Better then the Best Policy
• Quality Services

Getting Started with new Business is something tricky but not something impossible. Here few basic guidelines.

1. Plan your business idea whether you are going to involve in products selling or services.
2. After good selection for products or services go for the target market or markets for your services or products.
3. Look for some suitable location in reachable of customers.
4. Get together the Management team and assign tasks.
5. Get involve in start up marketing plan to introduce your products/services to customers.
6. Finally which is more important and comes first of all is to get financial plan to cover all those basic and setting up business.