Plans that have been drawn are stored under the My Plans tab and are private to the user that has drawn them. However, they may be shared to a forum and made public (if the forum is public) or available to a select group (that has been given access to the forum by the administrator). When plans are shared, they are copied. If the original plan is edited under My Plans, those edits will not be reflected in the shared version unless it is shared again. 

To share a plan (sketch), begin by finding an existing forum under the "Participate" tab and click on the forum name to enter that forum. In this case, I will share a plan to the Public Forum. 

You use an existing topic or create a new topic to share your plan. Here I will create a new topic called "New Idea for an MPA". (Note this is not a real idea. I'm doing it for demonstration purposes only.) 

Select the blue "Attach Plans..." link at the bottom of the text box. A dialogue box will open prompting you to select the plan(s) you wish to share in the forum. Select the plans and then click the "select" button. Your plan(s) will now be attached in the forum.