Hi fabio, welcome to TW! :)
Including info on your tennis website in your introduction thread is no problem, but please don't go posting about your site all over the place here. That would definitely be considered spamming. I did remove your one other thread in the General Tennis Discussion forum for that reason.
But, I have an idea for you...
Add a link to your website in your
forum signature then simply stop by TW often and participate in the many discussions. Your forum signature will then automatically display your website link below every message you post here. It would be a good way to get a bit of promotion for your website and also help us to make TW a little more active as well.