i would suggest bit more learning, ping google first for some tutorials...
i do not know how much do you know about protocols, what operating system do you use or anything else what can be helpful, telepathy is overrated... i assume you do have some limited knowledge of the computers
try this method, if you use any flavour of windows,
lmb = left mouse button
rmb = right mouse button
1. lmb "start"
2. in command line (white space on the bottom) type: cmd
3. expand black window and type: ipconfig /all
4. find Default Gateway, should be something like 192.168.1.1, not necessarily that as valid numbers are from 0 to 255, this numbers given as example are most common for tp-link router, make note of this number
5. type: ping (here type your numbers from Default Gateway)
6. press "enter"
first command "ipconfig" will tell you if you have network connection, second command "ping" will tell you how fast this connection is.
if you want to "discover" bit more about your network world, type in then in your black box type following: "tracert www.ibm.com"
this will tell you step by step how signal from your computer is going to ibm closest to your computer. of course feel free to tracert any imaginable server, be it yahoo, google, amazon or whatever comes to your mind.
hope this little explanation will help you, if you find this subject interesting - do google it (or rather use startpage.com or duckduckgo.com they do not trace your searches or memorise your online traffic), do not forget to to vote...