I've learnt a lot about Islam and so on on through google searches and stuff but its's still a lot to get my head round
But from what i can gather, The "Extremists or radicaslists" will change the story of islam to suit their agenda? So basically brain washing muslims? but not with the truth
It's not that they are changing Islam, they are cherry picking what they teach and emphasise, just like everybody else does within all religions.
An example, you often see at moments like this Muslim organisations trotting out the passage from the Koran that says,
“If anyone slays a person, it would be as if he slew the whole people: and if any one saved a life, it would be as if he saved the life of the whole people.”
This is typically what is taught to Muslims, and it is not a lie, it actually says that, but it's not the full truth either.
The full passage
"On that account: We ordained for the Children of Israel that if any one slew a person - unless it be for murder or for spreading mischief in the land - it would be as if he slew the whole people: and if any one saved a life, it would be as if he saved the life of the whole people. Then although there came to them Our messengers with clear signs, yet, even after that, many of them continued to commit excesses in the land."
Now you can see that if you can emphasise and teach the murder and spreading mischief in the land part you now have a path for killing to be allowed.
It is all about what is taught, and how it is taught. There is no "correct" Islam just as there is no correct Christianity, it is what each individual makes of it. Islam can be a religion of peace, or it can be one of war, and there are legitimate scriptural paths to either.