Jeffreys Prior from a gamma random sample

Can anyone get me started on determining the posterior distribution assuming a Jeffreys prior distribution on a random sample from a Ga(k,$\displaystyle \theta$) distribution

I did a similar thing with a binomial distribution but i had an example to follow so could kind of tell what i was doing. is this going to be similar?

Much appreciated if someone can show the framework of how to do this....

Thanks!

(n.b) i always use the Gamma distribution where the mean=a/b on Gamma(a,b)