The question is, Do you own the PC, not whether you have one.
If you are not the admin of the PC then I suggest asking whoever is to give you the correct privileges.
I'll personally not assist in trying to circumnavigate the original admin account unless you can provide any real reason to (I can make some assumptions but I'll refrain from stooping to that level). Get admins rights or the password or ask your parents.
I suggest creating an account with admin rights.
To get admin privileges on command prompt all you need to do is right click and run as admin.