Help on HELP

Help on HELP

I'm probably missing a simple point, but how do I get 'Help' in Zoho Sheet?  There seems to be no obvious link.  A specific example of where I need help is a situation where I want to create a line chart to compare the progress of two sets of values, but appear to be allowed only a single data source (i.e. one set of values)
Thanks for any enlightenment.