What dx cluster are you using?  You could simply google to find the documentation for the cluster type you are connecting to.  For example:

AR Cluster, search for: set ar6 cluster filter

CC Cluster (VE7CC): set ve7cc ccc filter

DX Spider: set dx spider filter

Those searches will point you to the documentation for the type of cluster in question.  If you take the time and read the documentation that is already out there and or search on YouTube for videos if you prefer that approach, you will discover how to construct a filter on your own and use a number of filtering directives to fine tune the filter to meet the needs of your station.  Google and YouTube are your friends.

There is not one filter that fits every situation, but if all you want to do is set a filter to show only spots for a specific skimmer server on an AR6 Cluster Node you would use this filter command:

That would give you all the spots coming from nc7j-# on an AR6 Cluster Node.  But why stop there?  You can also set the filter to show you any skimmer that spots you when you call CQ.  this is just a start, why not show spots for skimmers that reside in the states around you?  See if you can figure that out from the documentation from your skimmer type of choice:

There are many other options to set, but that will require you to dig in and read the documentation or find other resources out there from presentations or videos that describe how to use filters.  For example, K3LR has a good document on using AR6 DX Cluster filters: Microsoft Word - Using AR-Cluster V6.doc (k3lr.com)  (how did I find this?  I searched on Google)  The real instructions you ask for are: Use Google Search

Max NG7M