https://deadlystream.com/forum/25-tutorials/
There is a tutorials section on the site.
I have also written a short tutorial series covering some of what I learnt while working on my own project.
The first thing I would suggest you do, is get KotOR Tool, ERFEdit, K-GFF Editor, 2DA Editor and the Dialog Editor, there are a lot of programs available but these are what I use. ( KotOR Tool can work with most files, but it has always been described to me at least as quite buggy and should generally just be used to extract files from the game )
Though saying that, you might be better off starting with the Holocron Toolset, because it has everything built into one package, realistically you want to figure out what is best for you throughout the course of learning to mod the game.
The second thing I would suggest doing is familiarising yourself with the games file types and folder structure.
From there it's usually just a matter of opening up levels, editing files and repackaging the module, be it manually or using TSLPatcher to inject files into existing levels.
Then from there, peruse the tutorials and site, there is a lot of quite advanced and specific tutorials if you do enough digging around here.
Thor110