So you want to roleplay?
First you need to have picked a language for your race. This can be a real language (English taken by Spherons, Japanese taken by Hiiroans), or a conlang you created.
Second, you need to find the location you are contacting another race at. Is this a planet or their system? Find the page. If there is a "Roleplay" section already, move onto the next step. If not, create it.
Finally, using your language, send a message that explains what your character(s) are doing and saying.