How? SQL Cluster with multiple active nodes (not failover)
You don't get "load balancing" with SQL Server. There are a lot of "High Availability" features including clustering.

That is, you can't have read/write on the same data with multiple SQL Server instances.

You can off load reporting onto a snapshot, or replicate data between Instances, or "shared scalabl" but none is full OLTP on all data on every node.

You scale up, not out, for SQL Sever


SO: SQL Server load balancing
SF: How to load-balance SQL Server 2008 for high-usage ASP.NET applications?