Using CST to optimize parameters

I have a planar antenna designed in CST. I worked out the sizes using pen and paper, and made a parametrised antenna. My antenna is very close to the 2.4 GHz design frequency, but not perfect.
Is there a way to tell CST to vary one of my parameters (patch length) till the min S11 is at 2.4 GHz?
Thanks!

You use Solve-> Optimize.
'Settings' tab gives you list of parameters you used to define planar antenna structure, chose the feed line's width and gap. In the goals, set S11 goal to be -20dB or below. It will run.
Sometimes value doesn't converge then you can use Solve-> Time domain Solver -> parameter sweep and define your own range of values

Thanks, I found optimize and have been playing, but it never seems to get on the 2.4 GHz frequency, always a little either side, no matter how long I leave it going for! It keeps getting a better reflection co-efficient, but centred on, say, 2.402 GHz. Why is this!?

Perhaps the step size of the variables is too big.
However, 2.402 GHz should be ok, since often you can't manufacture the antenna with the needed precision and material parameters.
Also the simulation is not always 100% and neglect effects like a feeding cable or similar.