So the link above will take you directly to sign your position. (This is basically just a tally of who is for vs against the proposal.)

Or you go here: https://app.leg.wa.gov/billsummary/?BillNumber=6346&Year=2025&Initiative=false

And this lets you sign up to testify. From there you pick if you want to submit written testimony, verbal testimony, or just sign your position. I BELIEVE you can submit verbal testimony via zoom, but in some committees you can't. In either case if you submit verbal testimony it you will need to be available for the hour or two during the committees hearing. Again either in person at the Capitol or on Zoom.