This tutorial is for ALL Snapshots.

Snapshots usually can be found on the new in the minecraftforum homepage.
-------------------------------------With server--------------------------------------------

In the 1.3 snapshot and update there is a new folder, server. this is used to make it to where single player hosts a local server.i do not know if this will be removed in the future.

NOT: THIS IS FOR WINDOWS XP NOT 7, SOME OF THE STEPS ARE SLIGHTLY DIFFERENT IN WIN 7.

1.click the start menu
2.Type: "%APPDATA%" and click Ok
3.open on the folder named ".minecraft"
4.Place your server folder here.
5.open the folder named "Bin"
6.Place your minecraft.jar snapshot here.
7.Run Minecraft an it should work.

-------------------------------------Without server-----------------------

repeat all steps and skip step 4
and
instead of placing your server folder in the .Minecraft folder, create a new folder called "server". Then inside that folder create a text document that is blank and name it "Minecraft_server".
now, at the very top of your window click on "Tools" on the toolbar, and select folder options. in this window select the "View" tab. scroll down until you see "Hide extensions for known file types" make sure this is NOT
Checked. After that exit this window and return to your "Server" folder your text document should be now named "Minecraft_server.txt" rename it to "Minecraft_server.jar", it should change into a jar. run Minecraft and create a new world, if it say's something like "Its worse than that, hes dead Jim!"(don't ask why it say's that) then it did not work.

If you need screenshots i will post them but otherwise i will not.

I know that this most likely has been done before but i am making one anyway.
Please do not post hateful comments about how i "Stole this idea" or "{Insert name here} has already done this"

Thank you!