how to change variable conveniently?

I used several variable to adjust the shape of my model,but I dont know how to change them conveniently.I used to see someone open a small window as "property window" in which one can change the value of variable.
Does anyone know how to open the variable window?

Hi Oska,
Which software are you using? If you are using CST its very easy to change the variable. You just have to define it when modelling the structure and then using parametric sweep you can change the variables as you like.

Regards
Praful

I use HFSS.

Added after 7 minutes:

I have known how to change variable conveniently.Thank you.