Like in most forums, to attach pictures to your post you will need to either hotlink from a site directly (it the site allows) or from a picture hosting site which you have uploaded the picture to.
If you would like to have an online photo album then I recommend http://photobucket.com/. Else if you do not keep an album or usually just do a one off picture posting, then I would recommend http://www.imageshack.us/.
How to go about doing it?
For Photobucket.com
You need to register an account with them. After uploading your picture, the link for you to paste into forums will be given under the thumbnail of the picture in your album. Just highlight the link under the field 'IMG Code' and paste into the post box.
For ImageShack
After uploading your picture, on the next screen click on 'Show Advanced Linking' right at the bottom. right at the top copy the link under the field 'Direct link to image'. Paste the link you have copied into the post box, highlight the link and click on the 'Insert Image' button/icon on top of your post box.. There's also the thumbnail option from ImageShack if you have many pictures to upload, which are scaled down pictures which will be linked to the actual size picture upon clicking.
For direct linking from website
Copy the picture's link and then paste the link in the post box. Highlight the whole link and then click on the 'Insert Image' button/icon on top of your post box.
Note: Some sites do not allow hotlinking pictures from their site to save bandwidth. You are advised to hit the preview button first to see if the picture loads for you before submitting your post.
DIY method
After attaching many pictures long enough you will probably realise how to do so just by inserting the link between the 'IMG' tag codes which you can type out on your own like this:[img]www.mysite.com/mypicture.jpg[/img]
Testing how to post pictures here
After reading the above guides, you can go to this section to try whether you have figured it out: http://craversclub.com/forum/index.php?board=16.0
Image size guideline
The optimal viewing size for photos would be 800 x 600 (width x height). Please resize your pictures to this size both for the easier/faster loading of the pictures on fellow members' computers and to not strain the forum's resources when it has to automatically resize the pictures for the benefit of all users. Thanks!