Can't move the cursor while booting

Apology if this thread doenst belong here...somebody help me I want to install Mac os 9.2.1 but while im booting the system the inserted cd/os appear but I can't move the cursor to it, it seems the arrow keys malfunction and also can't do it by mouse and the only option is to press the (ENTER) key and if I press the ENTER key it will go back to the system hard disk and nothing happen.is there other way to reformat this system? and also i almost forget to mention I tried DMG files but im failed...the old OS is Mac os 9.0.2 ...any help will be appreciated...thanks...Ruel