The second photo is not dreads. Her hair was just twisted and a lot of hairspray was used to make a " temporary dread style". The first photo looks like it was possibly back combed. healthy dreads are not something that can be made. They grow and knot over time. It takes up to a year or longer before it is mature.
You can use a starter method like back combing or TnR. and have a bit of control over the thickness of the dread. Rule of thumb...dread will fatten up and be about as thick as the section.
As for extensions..I get the creeps just thinking about them. It is someone else's hair!!!!! you don't have a clue where it came from.. or what kind of person they are. If you attach their hair to your head you are carrying around THEIR energy. Right now in theCaribbean people with dreads are getting assaulted and having their hair cut offso that it can be sold to people like you that want instant long hair.
Or your can use the synthetic extensions..but they are plastic..who wants plastic hair?
Dreads are so special because they are all unique. They are a process that takes time and patience. Please search through the site. There is lots of information on all the different starter methods. But remember these are starter methods....they will not look like or be mature dreads for at least a year