Problem with run my first android program

I'm new for android. I try to write HelloAnroid but when I run the program, there are two errors.

1. Unable to open class file C:\Documents and Settings\Administrator\workspace\HelloAndroid开发者_开发问答\gen\com\example\helloandroid\R.java: No such file or directory
2. Error generating final archive: Debug Certificate expired on 22/11/2497, 2:29 น. 

I don't know why it happens. please help me with these errors.

You might see the answer here and as for "Error generating ..." see the answer here.

You need to compile the build and make sure your SDK is setup properly.

right click the project . go to properties.select java build path.click on the android sdk version.