Hard Drive Installation, how do you? Options

[eaks]

Hi everybody! I just had this new 120gb internal Maxtor HD. I'm on a mac g4 dual 1.25 G. I opened the comp, found the place to put the HD but there must be some kind of knob i dont find to let me insert the hd at its place. Someone could tell me where it is please? Also, is it ok if this new hd is ATA133 but that my mac is said to be ATA100?


thanks!