Triads are the first, third and fifth note of the chord. These are notes that harmonize with the root note of the "IV" chord. The 1b and the 4b.
The addition of the 7th note, flatted. makes this the flatted 7th chord and not a Triad.

I'm just learning this stuff, Zardoz. So please point out where I am wrong.
Is the 3d bent 1/2 step and 6b overblow, the flatted 7th's? or straight up the 7th?

Try the major triad or chord tones. For the IV chord they are the following:

Tonic: 1B
3rd: 2B
5th: 2D
7th: 3D bent 1/2 step
Root: 4B

The next scale is:

Tonic: 4B
3rd: 5B
5th: 6B
7th: 6B overblow
Root: 7B

Use these to make licks that sound good over the IV chord.