I know there are plenty of resources like this on the web, and the closest I've come was the answer to this question: ASP.NET Web API Authentication.
Basically, this is my requirement. Log in via android to my account on an MVC4 internet application I created (which uses SimpleMembership). It is NOT an MVC Web Api app, which seems to confuse things when looking at the various ways of achieving this.
I am attempting to use FormsAuthentication to set an authentication cookie, but I have no idea how to configure my android httpclient to actually send through this authentication cookie, or how to get MVC to save a session from my android app.
So far, this is what I've come up with on the MVC side:
    [HttpPost]
    [AllowAnonymous]
    public bool LoginMobi(LoginModel model)
    {    
        var membership = (SimpleMembershipProvider)Membership.Provider;
        if (membership.ValidateUser(model.UserName, model.Password))
        {
            FormsAuthentication.SetAuthCookie(model.UserName, false);            
            return true;
        }
        else return false;
    }
And I use the following java in my android app (sent over an SSL connection):
            DefaultHttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("https://mysite/api/login");
            List<NameValuePair> nameValue = new ArrayList<NameValuePair>();
            nameValue.add(new BasicNameValuePair("UserName", "foo"));
            nameValue.add(new BasicNameValuePair("Password", "bar"));
            httppost.setEntity(new UrlEncodedFormEntity(nameValue));
            httppost.setHeader("Content-type", "application/json");
            HttpResponse response = httpclient.execute(httppost);
            // etc etc
What I haven't figured out is how to receive the authentication cookie on android and send it back with each request to controllers with the [Authorize] attribute. I'm rather new to this so please forgive my ignorance!