There are two ways to get into your post to edit it; the editing process and functionality is the same from that point on for both.
Method 1 – Edit Directly
Navigate to the post in edit/secure mode (i.e. home page or News Centre) then click on gear icon and choose Edit Post.
Make required modifications and save/publish as usual.
Method 2 – SiteGovern
If you have created a post but not yet published it, this is the only way to edit it.
In SiteGovern, go to Recent Contents and choose the content type (shown on the right) from the dropdown.

Click “Edit” beside the post you want to modify:

Use the wizard to modify and publish the post as usual.