create a vector waveform file

[Altera_Forum]

I am trying to set up the values for input signals at different time period. However, I simply couldn't bring out the "Arbitrary Value" window out --- only part of the window shows up with options to set up the numeric value for the variable, but the other part of the window to set up the start time and end time is missing. This incompleted window showed up when I press "Ctrl+Alt+b" while the cursor is on the variable I need to set value on. Does anybody know where the problem is? How to fix it? Thanks in advance. 

 The tool I am using is Quartus II web version 13.0.0

[Altera_Forum]

I found out that the desired input waveform can be set up via drag the mouse and set up the values for different intervals. However, this method is very hard to make the input waveform accurate, that is, to be different values at different time intervals. Does anybody know how to bring out the menu to set up the start time and the end time along with the corresponding value for this interval?