We have an idea and a proof of concept, the idea is pretty specific to stealthy debuggin and binary code analysis .
The problem is that we are pure technical guys,
we don't know the market and don't know how to sell.
What is the best option to start doing market research?
What is the best option or the first step to build a startup / start selling it?
From the little information you've given, it's easy to assume that you've fallen into the trap of developing a product before figuring out what the market needs.
In this case, I suspect you've scratched your own itch, so assuming your target market is other techies, talk to them. Lots of them. Find out if your proof of concept is something they want and will pay for.
If yes, tidy it up, make it live, sell it, listen for feedback, iterate.
If no, listen to feedback, understand their problems, solve those problems (a new proof of concept), ask if they'll buy it, etc.
You don't need to be a trained salesman to talk about your product.
No-one is going to steal your idea and if your idea is that easy to steal and execute, it's going to get stolen the moment you launch it anyway.
Learn what you don't know, not what you know.
A product is as much, if not more about marketing and selling than building the technology.
Specifically, before writing a single line of code, having conversations directly with your customers to see if they have a need they will pay for is critical.
Thinking you can outsource sales and marketing is like non-techs saying they can outsource development. Even if you don't do sales ultimately, you need to know how sales technically work online, because sales online are very different (and more technical) than sales in the physical world.
Check out some books like Running Lean by Ash Maurya, or The Lean Startup by Eric Ries in a bookstore.
"There's nothing like great PR to kill a bad product" If you're just starting out, then you have a beta-ready product. The very first objective you need to reach is to have a market-ready product. To get there, you need a handful of users that you know really well and who can give you feedback on your product from an end-user perspective.
This feedback will be worth a lot: it'll help you make the adjustments necessary to build a market-ready product. And then, don't think of the product as just the executable code. Think of customer support, documentation...
So, to answer your question: start by evolving your product to be market-ready.