Server 2008 R2 question

[henrysin44]

I have a poweredge running Server 2008 R2 Datacenter. At my school we have terrible servers from the 90's and early 2000's but we have i5 laptops (not a good mix) everything is slow on any computer so this is where my question goes. At the schools login screen when prompted to enter your user and password there is an option to change the logon domain by typing (server address)\user. I can remote desktop to my server once logged on but i cant directly logon to my server at welcome splash. So how to i set my server up to do this.