How to do that to my iPhone

So, 2 or 3 weeks ago I jailbroke my iPhone with redsnow. So it says I must boot the phone via redsnow, or it will not boot. What should I do and its going to boot every time I restart the phone without booting via redsnow?

Try holding the top right button and hold the home button with the I Phone Shutdown.

If that doesn't work, then just hold the home button.

You got what is known as a tethered jailbreak. Hence the reason why you need redsn0w for it to boot properly.

Yes it will have to be done every time you need to reboot the phone until/unless you get an untethered jailbreak or remove the jailbreak