Looking for some help

Well i have looked around and read all the privlage articals on the site and cant seem to escalate my privlages on a computer. Well I am at school and i can get to the cmd. And i have tried the cacls way. This is what i have tried.

cacls /P Rich:F [C:\]

cacls /P Richerm F [c:\]

cacls /P Richerm [F c:\]

And a few other types. I dont understand what form the command is in. And it wont work for me. All I need to be able to do is install programs. (Or get admin access.) It is a local XP box. Now i asked Grind if he knew anything about this way but he said he doesnt remember and it has been a while sence he had dont it. But he recomended that i ask about creating an admin account. I dont know if ill be able to do this though because I am not an admin myself. Hopefully someone can get back to me on this one.

Net user username password /add

Replace username with your chosen user name and password with your choosen password. this will make an admin account on that PC, log into it and change the registry key for it the DWORD part to null zero or whatever it is…

also read this, it should be usefull… Getting any password on XP

so would that make a hidden admin account cause that is what im going for. Or is there a way to just take my login that i have now make it an admin but say that it is a restricted account that way the admin cant tell? (what i mean is on XP when you click the account it tells you if your an administrator or limited.)