Here are the steps on how you can create your own membership provide in asp.net mvc framework:
1. First you need to create a class that inherits the abstract class 
MembershipProvider and implements all the abtract members.
public class CustomMembershipProvider : MembershipProvider2. Override the function 
ValidateUser. Before you do this, I assume that you already created your database table.
 public override bool ValidateUser(string username, string password)
        {
            var user = (from u in _db.Users
                        where   u.Username == username
                        && u.Password == password
                        select u).SingleOrDefault();        
            
            if (user == null)
                return false;
            else
            {
               return true;
            }
        }
There are lot of procedures to override in the membership provider but I will let you do that with yourself.
3. Now, open your Web.Config and change the membership element to this:
<membership defaultprovider="CustomMembershipProvider">
             <providers>
             <clear/>
             <add name="CustomMembershipProvider"
             type="MVCApplication1.CustomMembershipProvider"
             connectionStringName="ApplicationServices"
             enablePasswordRetrieval="false"
             enablePasswordReset="true"
             requiresQuestionAndAnswer="true"
             requiresUniqueEmail="false"
             passwordFormat="Encrypted"
             maxInvalidPasswordAttempts="5"
             minRequiredPasswordLength="6"
             minRequiredNonalphanumericCharacters="0"
             passwordAttemptWindow="10"
             passwordStrengthRegularExpression=""
             applicationName="/" />
            </providers>
        </membership>
This are the settings for your membershipprovider.
THATS IT!
To test this you need to add dummy data to your users table.