What is OpenGL? And what should I do to play Minecraft?

Since we downgraded our PC from Windows 8 to 7 I never had the chance to play Minecraft. Please help!

Every time I try to open it it crashes and say this:

---- Minecraft Crash Report ----
// Uh… Did I do that?

Time: 6/7/14 2:04 PM
Description: Initializing game

org.lwjgl.LWJGLException: Pixel format not accelerated

(Blah blah blah, It's kinda long so I didn't copy it)

Minecraft Version: 1.7.9
Operating System: Windows 7 (x86) version 6.1
Java Version: 1.7.0_55, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
Memory: 4945752 bytes (4 MB) / 26808320 bytes (25 MB) up to 518979584 bytes (494 MB)
JVM Flags: 3 total; -XX: HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M -Xmx512M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.7.9
LWJGL: 2.9.1
OpenGL: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.
GL Caps:
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs: []
Current Language: ~~ERROR~~ NullPointerException: null
Profiler Position: N/A (disabled)
Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Anisotropic Filtering: Off (1)

Java Version: 1.7.0_55

your version of java is way out of date,

go to > http://www.java.com/...va.com/en/
and get the latest version which is 7 version 60

after it is installed and you are still getting problems,
then go to the minecraft site and get help there not here.
.