To do that you have :
1-Index your local event log or local performance. to do that in splunk web go to SETTING--ADD DATA---MONITOR then select what you want to monitor( processor, memori,system ......)
2- you can create a new index for that.
3- once you have index your machine data,you can now search the index where you put you machine data.
4- build queries using events from that index and save them as Dashboard with title NPRmydashboard_activity.
It's difficult to build queries without seeing some sample data. Can you please provide some?
Also, it's not clear what you want the results to be. For instance, you say "memory, disk, and network activity." Do you mean in real time? The last time you polled? An average over the last minute, or hour, or day?
Please read the search documentation and see if you can construct the search yourself first. Please post the searches you tried, what the searches returned, and what results you were looking for.