Sharon,
Tagging someone is as easy as
@Altheabyanothername. Use the @ symbol, then the member ID (not their name unless the two are the same). No spaces between the symbol and member, but one space after the member ID.
Don't know.
If you mean add a photograph from the database to a post, go to the database entry of the plant you want. I will use SDB Iris 'Blue Oasis' as the example, here. Once in the entry, click on the image you want to post to the thread. The last line of text just above the image will be the BB Code, then a string of characters. Copy that string including the leading and ending brackets. Paste to your post and voilà.
This is the code for one of my images. Left the end bracket off so you could see what I am talking about, then put the whole string in so you could see the image.
[db_photo]366641[/db_photo
To add images from home to a post: at the bottom of the post box is a button that says Upload an image. Click it and follow the steps.
To add images from home to the database: go to the plant entry. To the left will be a link that says Upload a photo. Click it and follow the steps.