A beginner needs help

Hi guys,
I'm completely new to Elasticsearch world.At work akse me to install ELK and compare it with Splunk that we have running.I have followed this link
https://www.digitalocean.com/community/tutorials/how-to-install-elasticsearch-logstash-and-kibana-elk-stack-on-centos-7
to build an ELK on cent os 7 and it is working to pars syslog messages.However,I can not pars some other files that we are using in splunk.I have directory of windows logs in our NAS as I know they should be log4net log files. I've tried several solutions to pars my files and send output to my Logstash but still unsuccessful.I use filebeat to ship my files to ELK server but i"m not sure if it's a right way to do it.
How can I pars log4net logfiles in centos7 and what is the best way to do it.If i don't use FIlebeat what is the alternative solution to send files to Logstash?
Any help would be appreciated.

I use filebeat to ship my files to ELK server but i"m not sure if it's a right way to do it.

That's a good choice.

How can I pars log4net logfiles

If you show us an example of what they look like we can help.

Thank you for your help,if I can learn how to create filter for one of my log files I'm sure I can continue doing this for others as well.Here is the part of log file:

2013-08-13 16:05:10,241 [1] ERROR NHibernate.Util.ADOExceptionReporter - Session is currently disconnected
2013-08-13 16:05:10,469 [1] ERROR LogExceptionHandler - Unhandled Exception
NHibernate.HibernateException: Session is currently disconnected
at NHibernate.AdoNet.ConnectionManager.GetConnection()
at NHibernate.AdoNet.AbstractBatcher.Prepare(IDbCommand cmd)
at NHibernate.AdoNet.AbstractBatcher.ExecuteReader(IDbCommand cmd)
at NHibernate.Loader.Loader.GetResultSet(IDbCommand st, Boolean autoDiscoverTypes, Boolean callable, RowSelection selection, ISessionImplementor session)
at NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies)
at NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies)
at NHibernate.Loader.Loader.LoadEntity(ISessionImplementor session, Object id, IType identifierType, Object optionalObject, String optionalEntityName, Object optionalIdentifier, IEntityPersister persister)
at NHibernate.Loader.Entity.AbstractEntityLoader.Load(ISessionImplementor session, Object id, Object optionalObject, Object optionalId)
at NHibernate.Loader.Entity.AbstractEntityLoader.Load(Object id, Object optionalObject, ISessionImplementor session)
at NHibernate.Event.Default.DefaultLoadEventListener.LoadFromDatasource(LoadEvent event, IEntityPersister persister, EntityKey keyToLoad, LoadType options)
at NHibernate.Event.Default.DefaultLoadEventListener.Load(LoadEvent event, IEntityPersister persister, EntityKey keyToLoad, LoadType options)
at NHibernate.Event.Default.DefaultLoadEventListener.OnLoad(LoadEvent event, LoadType loadType)
at NHibernate.Impl.SessionImpl.FireLoad(LoadEvent event, LoadType loadType)
at NHibernate.Impl.SessionImpl.Get(String entityName, Object id)
at NHibernate.Impl.SessionImpl.Get(Type entityClass, Object id)
at NHibernate.Impl.SessionImpl.Get[T](Object id)

I've tried to use Grok constructor but I was not successful.
Thank you for your help