//go to Minecraft.java, in the run() function, put this code after the first try catch:
session = new Session("Username", getSession("Username", "password"));

//put this in Minecraft.java
public String getSession(String user, String pass) {
	   String userName = user;
	   String password = pass;
	   String result = null;
	   try {
		   String parameters = (new StringBuilder("user=")).append(URLEncoder.encode(userName, "UTF-8")).append("&password=").append(URLEncoder.encode(password, "UTF-8")).append("&version=").append(12).toString();
	       result = Util.excutePost("https://login.minecraft.net/", parameters);
	   } catch(Exception e) {
           e.printStackTrace();
	   }
       if(result == null) {
           return "";
       }

       if(!result.contains(":")) {
           if(result.trim().equals("Bad login")) {
               //showError("Login failed");
           } else if(result.trim().equals("Old version")) {
               //loginForm.setOutdated();
               //showError("Outdated launcher");
           } else {
               //showError(result);
           }

           //loginForm.setNoNetwork();
           return "";
       }

       String values[] = result.split(":");
       return values[3].trim();

   }