When you say lead are you talking improv, making stuff up on the fly? For that you need to know at least some theory and how keys and scales fit together. What makes sense based on the music being played.

For Blues, that is a deep dive in itself and this site can get you started - Anders has lessons in Blues - but it just touches on the subject. To get deeper you need something more speacialized like the lessons taught by Jeff McErlain on Truefire or some other sites that go deeper into the genre and even deeper into artist studies.

This site is good at touching on many aspects of guitar but isnt designed to go into as much depth as some specialized sites. I use this site for what I would call the fundamental grass roots stuff and use others sites for other things.