I just downloaded jre7 (C:\Program Files\Java\jre7) and eclipse (Eclipse IDE for Java Developers Version: Indigo Service Release 1) (C:\Documents and Settings\mike\Desktop\eclipse2) and everything is showing up with a red underline in my code. What is causing this and how can i resolve it?

I also get a "Could not find main class." error when I run anything. And this error:

```
java.lang.UnsupportedClassVersionError: Miner_and_Alchemist_v2 (Unsupported major.minor version 50.0)
    at java.lang.ClassLoader.defineClass0(Native Method)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$100(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClassInternal(Unknown Source)
Exception in thread "main" 

```