Minecraft: How to change block textures?

Not with a texture pack. I can't figure it out. I opened up the jar file with winrar and found the gravel file under the textures. It was a single side of the gravel since all sides are the same. I edited it successfully so in place of the small 16x16 gravel texture was the small 16x16 new texture i wanted in its place. I then hit save, it said "this file was changed, do you want to save it" something like that, i hit yes, it did it successfully, and when i tested the file by opening it, it was the texture i wanted. There was no other png file named gravel. But when i opened minecraft the gravel was still the same. Did i do something wrong or open the wrong texture file?

Minecraft Graphics Card not working?

My minecraft won't launch because of outdated graphics card. I went to the fix problem and checked my Intel graphics card for updates, but the site said the graphics card was current. My Graphics Card is Intell 2000.

Minecraft crashes on Windows 8?

The error detail is pixel format not accelerated, I tried everything; Compatibly mode, update drivers, install 32-bit java. But it still the same error(pixel format not accelerated)
Here is a detailed error information:
---- Minecraft Crash Report ----
Description: Initializing game

org.lwjgl.LWJGLException: Pixel format not accelerated
at org.lwjgl.opengl.WindowsPeerInfo.nChoosePixelFormat(Native Method)
at org.lwjgl.opengl.WindowsPeerInfo.choosePixelFormat(WindowsPeerInfo.java:52)
at org.lwjgl.opengl.WindowsDisplay.createWindow(WindowsDisplay.java:244)
at org.lwjgl.opengl.Display.createWindow(Display.java:306)
at org.lwjgl.opengl.Display.create(Display.java:848)
at org.lwjgl.opengl.Display.create(Display.java:757)
at org.lwjgl.opengl.Display.create(Display.java:739)
at azd.Z(SourceFile:367)
at azd.e(SourceFile:689)
at net.minecraft.client.main.Main.main(SourceFile:103)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
org.lwjgl.opengl.WindowsPeerInfo.nChoosePixelFormat(Native Method)
at org.lwjgl.opengl.WindowsPeerInfo.choosePixelFormat(WindowsPeerInfo.java:52)
at org.lwjgl.opengl.WindowsDisplay.createWindow(WindowsDisplay.java:244)
at org.lwjgl.opengl.Display.createWindow(Display.java:306)
at org.lwjgl.opengl.Display.create(Display.java:848)
at org.lwjgl.opengl.Display.create(Display.j

Please WATCH THIS YOUTUBE VIDEO?

I have recently made a YouTube video of Ariana Grande's song 'Problem' remade into Minecraft note blocks. I made this 100% by ear, and as you can probably tell it was very hard to make. I would appreciate it if you could all watch it and maybe give it a like as it would help me out a lot.

Here is the video link:

And yes this was probably the dumbest thing I could have done to help it get views but yolo!

Thanks, ~The Jachael123 Team~
Please WATCH THIS YOUTUBE VIDEO

How much would a computer with these requirements cost?

I would like to get a computer that will run minecraft and I read that with these requirements it will run better
CPU: Intel Core i3 or AMD Athlon II (K10) 2.8 GHz
RAM: 4GB
GPU: GeForce 2xx Series or AMD Radeon HD 5xxx Series (Excluding Integrated Chipsets) with OpenGL 3.3
HDD: 1GB
Latest release of Java 7 from java.com
So just an average cost for a computer with all this please and thank you
Oh and does it matter if laptop or desktop?