Community park groups rarely have to carry out promotion work on a big scale but being able to create a poster or write a press release, advertise an event or activity, provide a leaflet to inform people about your group or write a newsletter to communicate to your group members, are useful skills.
Running your group
There are a lot of skills required for the day to day management of your group, but help can be found here.
This overview and reference is aimed at helping Friends Groups.
This is a sample set of minutes for a groups committee meeting.