The major "building block" in accompaniment is chords. And the sequence of chords.

At the listed web sites you can find chord tables and theory, pattern samples, software for drum/beat, and some software programs for chord detection.

Chords

Chord Finder

Gitarre - Guitarre - Guitar

Guitar Chord Finder

Transpose Chords in Lyrics

Chord Progressions

All That Chords Software

web.transpose.tool

Riffstation - Chord Recognition

Music midi drum patterns

Prosonic Studios Midi Patterns

Drum Track Zone

Arabic Rhythm Patterns

EKN Midi's Drums

Free MIDI Riffs

Drum/Beat Software

Gradywerks MPG64-R Drum Machine

Monkey Machine - online drummer

Yamaha - One Finger Chords exe

Doctor Rhyme

Hammerhead Rhythm Station

Drum Station

MIDI Drum Files

Chord Software

Chords for beginners exe

Chord Pulse

Chord Pulse Lite