It would be helpful if you could elaborate a bit more about the kind of quantification you aim to do. Regardless, if you have not fully committed to it yet, I would recommend you check out some other tools that might be easier to work with.
For histology I found QuPath to be reasonably user friendly and more importanlty, it comes with good quality documentation for most basic analysis. If you follow the link, you will find information on how to install it (it’s free), tutorials on how to identify and measure areas, separate the haematoxylin and eosin channels and quantify cell numbers etc.