Setting up an extended ACL?

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Trying to get my head around this, but it's a nightmare!

I have a network, and need to restrict aceess from another network. The ip of the network to restrict access from is 192.168.2.0. My task is to deny all acess apart from the terminals in the lower hald of the address range (2-127). So any address from 192.168.2 - 192.168.2.127 is allowed, everyting else should be denied.