I know, it's not easy when you're new.
Okay, do this in a separate window or tab (depending on browser, version and personal preference).
Open a second session in E, (you can have as many as you like open at once), and click the "Click friend and enter" link. The screen you get lists all the various forums that exist. Down the right hand side are the "Play By Post" forums. You need to pick the forum most appropriate for the content.
Hover your mouse over each Orange heading and you will see a description of the expected content of that forum.
This RP MUST go in exotic, because shape shifters are automatically classified that way.
But you need to decide the level of "rough stuff" allowed. If it is just vanilla sex and romance, or non-sexual and relatively non violent. it goes in "LIGHT". If bondage and torture is allowed, but the characters must give consent to be bound and tortured, then it goes in "BONDAGE". If non-consensual actions, such as rape, kidnapping, forced bondage, etcetera, are allowed, it goes in NON-CONSENSUAL. Note: Non-Consensual refers to the CHARACTER not the PLAYER! If the player does not consent to an action then it must not happen. If stuff such as bestiality (with actual animals), water sports, scat (No thanks), incest, extreme violence, forced drug use, stuff like that, are allowed, then it must go in EXTREME.
If in doubt, take your best guess. You won't get in trouble for getting it wrong once in a while and the staff will move the thread. Only if you get it wrong persistently will they warn you about it because they'll assume it's deliberate!
As for which forum within the group, it must go in small groups.
Open a thread with the title you want for the game, followed by "OOC", and post a link to it here, and we can shift the discussion there.