Coding Question - Dynamic Dropdown

Hi
probably answered somewhere else so I apologise upfront. New to these forms so sorry.
I want to put a dynamic dropdown box on form
I want it to call from my linked database - 'svebDB1'
table - tblSchools
field - schoolNames
and populate the drop down. I have ticked the allow field to be populated dynamically. Not sure of parameter and where it points to.
I am unsure what approach to use. I have looked at your examples but most point to posts.
The other thing I wanted to do was filter by 'Enable Conditional Logic' using 'postcode' (I have that field on my form and each school has their postcode listed in the table - tblschools - 'schoolPostcode'
Thanks in advance
Cheers
Peter