You should start with major triads and learn every chord in every inversion all the way up the keyboard with both hands ( seperate hands , not both at the same time).
Start with the white keys, so C, D, E, F, G, A, and B.
The C chords would be C-E-G, E-G-C, G-C-E, and so on from the bottom of the keyboard all the way to the top.
The D chords would be D-F#-A, F#-A-D, A-D-F# etc
You’ll also want to learn at least B flat and F sharp too if you plan on jamming with a broad range of musicians.
Then learn all the minor chords – so C would be C-Eb-G, Eb-G-C etc You should know all of them.
You should practice every chord all the way up the scale as well – C –C# - D –Eb – E – F – F# etc
And keep doing it with both hands at the same time until you can do it with your eyes closed.
That will get you started J