You need somebody to show you the basics. I got an introductory 1 hour course from a friend and that made it.
As others said, you need to go sideways to get into orbit.
This translates to going vertically for 5k meters,slightly sideways (e. g. 10°) until 10k, then like 25° until 15k, then keep going until 30k, as you feel like you can go more sideways without making your rocket explode, do it. Do it by trial and error if needed, without trying to minmax, better to go more vertically and then horizontal. Consider that you want to keep going up so that your apoapsis (highest point of the orbit) is above 70k, which is when there is no air at all. You can notice that the "space" music starts only when you hit 70k.
Once the apoapsis is out at above 70k (ideally 80 or more), shutdown engine and wait in map until spaceship is about at the apoapsis. When that happens, point sideways (same direction you were always doing) turn on engine and keep them running until the periapsis get to 70k or more. If it's less than 70k, you will fall back.
That's about it!
To continue, start playing with plotting in the orbital map, it will give you a good idea of what you can do. Keep in mind that the way you measure how far you can go is by checking the spaceship delta V.
Good luck!