Problem is you've been a bit vague. What have you tried, if anything? What version of the server are you running?
Apologies for the vaguesness ! My aim is Freeradius authenticating against OpenLDAP for the MSCHAP bit (there are various examples out there showing how do do this such as http://vuksan.com/linux/dot1x/802-1x-LDAP.html) , but uncommenting the LDAP elements in /server/default just seems to kill off the working eap-tls config. Currently on version 2.1.12.
Suggest:
1. Ensuring you're on a recent version of the server, 2.2.3 2. Follow the deployingradius docs linked above on a test server 3. When you understand how it has all fit together, migrate the config to your production system, with your existing TLS CA/certs
As with all systems tasks, if you're new to it then make small changes, check your results into version control after each success, follow the docs.
If you've got specific questions, people can give more specific answers.
Will take a look.