Password Help

OK, I am back. I posted here yesterday about how I just received my new Mac Mini...I just ran into a problem and I was wondering if anyone knew what I could do to fix it? I have already done a search for help, but I didnt come up with anything. Apparantly, yesterday when I set up my new Mac Mini I entered a password for my account. Now, I do not know what that password is. It is not the password that I normally used because I have already tried that. I really have no idea what the password is and I need the password to install some software. Is there any way that I can find out what the password is? Also, how would I go about re-installing OSX since I dont have my password (I have to enter the password to re-install it). Thanks for your help!