Where do I set up the source model?

[CHsCCHHSS]

I'm a new user. I'm following tutorials. The tutorial tells LORA to choose a source model, but I can't find it in my program.
I don't have a menu to choose a sauce model. Where is it?
In the video or picture, the source model menu appears on the LORA tab,
but in the version I downloaded a few days ago, there is no source menu.

[5KilosOfCheese]

If you choose a model from the dropdown menu, the system will download it. Alternatively you can navigate using the folder icon to the folder in to which you have downloaded a model and choose that.