I want to go to 3 islands, but how do i go to another without losing the one im owning at the moment?

 

It depends on the server (I don't think on .org) but you may be able to /tpa or have a donor /tpahere.
Besides that, you can't really live on other islands, just one.

 

well on .net you have /home and /homes so u can be on 2. unless you TP