I'll attempt to answer, although I haven't started a technology company, I do work for a technology startup and have taken businesses from cradle to the grave. This answer won't go into the legal side of things, but will touch on a few areas I believe to be important, it will likely leave you asking more questions, but provide you with something to think about going forward.
I will also mention, this will be answered in a way that assumes you plan to start a software-based technology company rather than hardware as I believe I can provide more value here.
First, you're going to need an idea. What is going tech company going to do? What problem is it going to solve? This is an important question to ask yourself before you begin, you need to understand if there is a real use case for your idea. You will see many companies created that are searching for a problem rather than solving one, try to avoid this and stay true to yourself about the company and vision that you want to create.
Do you have enough capital to start your own business? Will you be starting this alongside other responsibilities or will you be dedicating your whole time to your idea? Your skill set will have an impact on how much capital you actually need, you're going to need someone to develop your idea. There's no fixed amount of capital you're going to need and you're either going to need enough to cover the time you spend on the project if you plan to do it full time and further money to pay for development should that be required.
How are you going to get your minimum viable product? Do you have a development team or can you develop yourself? Ideally, in order to reduce costs you will want to develop this yourself, potentially this could be completed by a friend or co-founder if you're lucky enough to have a suitable candidate in mind. Within the development phase you will be creating your product from scratch and setting the foundations for your product going forward, you will need to make decisions surrounding what technologies you wish to develop your product with and the overall architecture.
4. Planning & Execution
As mentioned previously the first thing you aim will be to is to get a minimum viable product? but what does this mean? Well, this is the minimum product you could deliver to your customers. In order to do this, you will need to look at all of the features you wish to have within your product and prioritise them in a way which allows you to clearly understand which ones are the highest priority, there are methods for this such as Moscow requirements, but I won't go into too much detail about that now. By doing this you will be able to understand how long it will take to get your product to market and begin to create a clear and concise plan of how you plan to achieve it, which features will you develop first, how long will it take? etc.
It's not going to be easy, there will be many problems that occur, deadlines will be missed, features will not be completed, and overall many fires to fight, but the key is having the ability to stay focussed and look past that. You should always keep an eye on the end goal, keep looking forward to the vision of what you want to achieve and constantly assessing the steps you're taking to get there.
Again, I will mention that the answer provided only goes into a few high-level pieces of the puzzle and there are other things that will need to be completed, although I believe my answer will provide you a key few things to think about and spark further thought.