As Leanne says, you can link to your website in your signature.
You can't just post your website link in any post about rabbit show jumping though as that would count as spamming.
If, for example, someone posted saying 'Does any one have any photos of rabbit show jumping?' and you have photos on your website, you could then link to the page on your website with the photos. However, if they are posting their own photos or just talking about it in general and you just posted ' Look at my website about it [link]' that would be spam.
The forum is about people chatting and interacting so any post that is just made out of self promotion/interest would be frowned on.