Combo Box

Total noob here guys. I was wondering if there is a way to select a value from a combo box and activate (check) certain check boxes? If there is a way how would i start the code?

Example:

Checkbox has three values "One" "Two" "Three"; If the "One" is selected then checkbox 1 should be checked. If "two is selected then check boxes 1 and 2 should be checked and so on. If nothing is selected in the combo box no check boxes should be checked.

i Have this much so far:
(in validate for the combo box))

if(event.value == "One")
{
this.getField("Check Box3").checkThisBox(0,true);
this.getField("Check Box2").checkThisBox(0,false);
this.getField("Check Box1").checkThisBox(0,false);
this.getField("Check Box4").checkThisBox(0,false);
};

if(event.value == "Two")
{
this.getField("Check Box1").checkThisBox(0,true);
this.getField("Check Box4").checkThisBox(0,false);
this.getField("Check Box3").checkThisBox(0,false);
this.getField("Check Box2").checkThisBox(0,true);
};

if(event.value == "Three")
{
this.getField("Check Box1").checkThisBox(0,true);
this.getField("Check Box4").checkThisBox(0,false);
this.getField("Check Box3").checkThisBox(0,True);
this.getField("Check Box2").checkThisBox(0,true);
};

else
{// Restore values
this.getField("Check Box3").checkThisBox(0,false);
this.getField("Check Box2").checkThisBox(0,false);
this.getField("Check Box1").checkThisBox(0,false);
this.getField("Check Box4").checkThisBox(0,false);
}

I know my coding is off somewhere but i dont exactly know where. Thanks in advance.