Of course, creating any kind of game is such a broad topic that it's going to be very hard to "teach you" in a forum post, but hanging around the places I listed above, lurking a bit and peeking inside other people's code (when they leave it unobfuscated for that purpose) should, over time, allow you to get a good understanding of what to do. Haha~ I find it hard to make a dating sim game with it. Just worry about how to make it into a dating sim game like make the relationship between you and the guy or girl closer. I'm afraid that for that you'll have to dig around for tutorials on the DSE (Dating Sim Engine), as my field of knowledge is more on drawings than coding.
Which part of my post do you find particularly hard to understand? After running Renpy's launcher I chose "Options" from there and created a Projects Directory.
As far as I know the Novelty engine is a WYSIWYG program, so it's probably easier to grasp than Ren'Py, you could try visiting their forum and seeing if anyone has posted any example game there.I then unzipped the contents of the DSE inside my Projects directory.Then I got back to the main Launcher page and chose "Select Project" - the DSE is already there.The Star Ocean series of RPGs also feature dating sim elements in a similar manner.Some Japanese dating sims may allow the player to have romantic or sexual relationships with characters in their teens.
There are also GL games, which focus on female/female relationships, and BL Games, which focus on male/male pairings.