Control access to Internet with Access code

I have a wireless connected by ethernet to router. Router is shared between the diffrent units in my building using a cat5 cables. Is it possible for me to control access to internet using my PC by assining some kind of access code?
I have very limited knowledg in computing

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Yes, it's possible.
First of all, I'd like to know if you have the control over the wireless router, you know, to set the router via web browser.
If it's so, it's very simple, you must set a password on , and the all the computers you have (one is master) must be set according this password.
The acces to router is someting like 192.160.x.y
then you go on wirelless button, then you must go to wpa button and then you select on WPA mode WPA+WPA2-PSK
the on authentification you matk the radio button "Preselcted key"
the down you enter a password you want and than SAVE
That is for the router.
For the computers next time
so long