can anyone help?

mojang.com

An easy way to download and keep up with the snapshots is to

1. go to the minecraft forums
2. Scroll down until you see the last snapshot update
3. click on client
4. wait for it to download
5. while you wait go into your minecraft folder (for mac its user/library/application support/minecraft/) Go into the bin and delete minecraft.jar
6. now copy and paste the downloaded minecraft.jar into the bin and voila! Your minecraft has just been snapshot!