Hi Sandra,
If I understand you correctly, you're asking if there are photos for other cultivars for a particular type or species of plant beyond what is shown on the database pages? Generally the answer is no - the photos shown on the database pages are those that have been added to the database. There may well be photos that have been uploaded in the forums by users and the system tries to locate these (if you open the plant entry in the database there may be a list of forum threads towards the bottom of the page that may or may not have a relevant post in it... but it can be hit-and-miss, as the system isn't perfect).
In regards to your second question, you can most certainly add a photo of your plant. If it is just a selection of a species (rather than a hybrid), you can add it to the generic species entry. Otherwise, if it's a hybrid plant and you only know the genus, then you can add it to the genus page. If you don't know anything about it at all, then there is
The bin of unidentified photos (Holding_space)