If you want to view what is currently running on your Linux server you can call the following command;
top
This lets you see every process that is running and see at a glance what is roughly consuming the most resources on your machine.
There are better tools for digging into this information but top will give you a good quick overview.
Once top is running type q to quit it.
If you want to read up more on top you can read the man page by typing man top in your terminal.