formz is a Form building extra that allows you to get forms up and running on your website. You can store the information inside the database or send a email and store in database.
You can find the documentation here: Formz Documentation
Install using Manager Package Management
FormIt http://modx.com/extras/package/formit
FormItFastPack http://modx.com/extras/package/formitfastpack
If you are installing from the package provided inside the packages directory, just copy the file into your MODX core/packages directory and then do find file locally inside of your Manager Package Management interface.
Once the package is installed you can setup a template variable and assign the formz input type and output type to it. Go to a page that has the template variable assigned to its template, and you should now have an empty dropdown menu.
You can now start to create Forms by going to the components menu Formz Builder.
Any comments or issues please raise that using the issues system.