Apex class to save custom object data.

Save Lead with custom fields:

   public PageReference saveLeadData() {
        Lead l = new Lead(
        P_PERSONID__c = 6663649,
        ROLEID__c = 5898589,
        P_PROJECTID__c = 10796447,
        Salutation = 'Mr.',
        FirstName = 'saket',
        LastName = 'saraf',
        Title = '',
        Phone = '98920000',
        Email = 'saket.saraf@gmail.com',
        Street = 'Land Adj 23 Lisle Street',
        City = 'Loughborough',
        State = 'Leicestershire',
        PostalCode = 'LE11 1AW',
        Fax = '',
        WebSite = '',
        LeadSource = 'Reserved'
        );
      
        try {
          insert l; // inserts the new record into the database
        } catch (Exception e) {
          ApexPages.addMessage(new ApexPages.message(ApexPages.severity.Error,'Error adding Reserve List.'));
          return null; //Use Page.newPagename
        }
        return null;   //Use Page.newPagename  
     }