If you only want to show the code, and you've kept things simple, you could upload the
script.rpy
file here as an attachment. Just use reply, then the "attach files" button at the bottom left of the editor box.
Alternatively, you could reply here... then when you're ready to type... press the button on the forum editor toolbar that looks like three dots and a down arrow ( ...v ) - it's "insert {something}", pick "code" from the dropdown list, change the language to "Other -> Python" and copy/paste your code into the box, then hit "Continue"... it will post your code in a box that keeps the important stuff, like indenting.
If you want to show off your whole "game" so far, then you need to use the RenPy launcher to
[BUILD]
the project. That will create a
.ZIP
file containing a playable version of your game. Upload that to one of the
approved file hosting services recommended by F95, then post the link to the uploaded file wherever you like.
There are extra steps and rules you need to follow if you want to actual "release" your game onto F95's latest games list - but it doesn't sound like you're at that stage yet.