1. Google your two senators and get their office phone numbers.
2. Call each one, identify yourself as a constituent [they love that], and urge the senator [by way of the staffer who answers the phone, of course] to support the call by Senators McCain and Schumer for a select bipartisan committee to investigate Russia's interference in the election. Make it clear that you will not be satisfied with Senator McConnell';s proposal for a regular [i.e., Republican controlled] committee.
A tiny thing, but it takes no time at all.