Sure!
On the left side of the website you should see a link that says "Photos", above "reviews" and below "Forums". Click on that and then upload photo. If you need to resize a photo you try this website
Online Image Resizer - Resize digital photo, images or pictures online!
Once you have photos uploaded to 3reef when posting a ...post you click on the little image icon and copy and paste the adress of the photo. (right click the photo and click properties for adress).
hope this helps!