To add a post - click on +Add new Post at top right (if it is not there, you are not signed in - see link at top of page); fill in the details, then click on black button below.
To later edit it, click on the post header to display it, then on +Edit at top right.
If you wish to give somebody your contact details, you may prefer to do so by personal message (click on little envelope at top of page, then on +Compose) rather than putting it in a post which is visible to everyone.
Click on a category to display all posts that have been allocated this category:
Recipes - Food