Here are some commands to discover system hardware and software configuration:
Run the commands in a "terminal" (Ubuntu: Applications | Accesories | Terminal).
The bash shell runs in the terminal to input, interpret and run command lines.
To find out more about a command, do either: 
  command_name --help
  man command_name


Architecture:   arch     
CPU:    more  /proc/cpuinfo
         (Model name, speed, cache size, "bogomips")
RAM:    free  -m 
         (Total RAM memory in MB)
Disk:   df  -hlT 
         The /dev/sdaX are them.
         (Sizes and types of disks/partitions)
PCI devices:   lspci     to see PCI devices                    
IRQs:     more  /proc/interrupts

OS:       uname -rs 
            (kernel version and release)
          more /etc/lsb-release 
            (Linux distribution)

hostname:             hostname
system uptime:        uptime
sytem time:           date
list all processes:   ps aux
process activity:     top   (q to quit)
user accounts:        more /etc/passwd
logged on users:      who   
                      w
last         # previous logins of users
lastlog      # last login of every user


ifconfig     to see the IP address of Ethernet
iwconfig      for wireless connection
  eth0 is the first ethernet interface. 
  UP and RUNNING is the status you want to see. 
 (lo is the loopback device, ignore it.)
 HWAddr is the 6-byte (in hexadecimal) MAC address of the network interface
card/chip/controller (NIC), unique in the world. 

du -sh       amount of disk space used by the working directory and all its subfolders

locate name     list of all files and folders that have 'name' as part of its name
                (assumes your system has slocate/updatedb database running)