I am new too and when I do play at church it is just me and the drmmer so I have to play bass lines however when I get ready to start fully playing (on Sunday's) there will be a very skilled bass player, an organ player and a drummer, as a beginner how do you play filler chords, or fully two hand chords. I know most worship songs (that I listen to) the keyboardist always leads..
As a keyboardist, you can think of yourself as almost another drummer...The organist does pads (sustained chords, maybe some fills) but you can drive the rhythm. When you have a bass player, you can do the root of the chord up one octave with your left hand - that's how I started. What your RH does depends on the speed of the song - slow worship chorus arpeggios (chords one note at a time) are good, like a harp or finger-picking on the guitar. For faster songs, pounding block chords, like faster strums on the guitar.
So for example on a C (CEG) chord on a faster song...
Bass - (8th notes) C E F F#G A Bb B
Piano LH - C G C G (alternating root and 5th in quarter notes for a start. There's lots of different patterns)
Organ - depends on the player, can be a wall of sound, the real good ones attack with both hands and feet!
Piano RH - 3 or 4-note chords, in a rhythm more or less following/supporting the vocals (do NOT play the melody for them unless they absolutely NEED it). Hymns in mainline churches are a different story - but I played "Amazing Grace" tonight with a mild 9/8 feel and people knew the melody enough that I only played it for the intro. The real fun with chords come when you invert them/add color tones (those 6,7,9,11,13ths you hear about).
There's lots of different styles, so this is only a starting point - eventually you'll build up enough skills to come up with ideas on your own...
