I am trying to figure out how to calculate the ratio of CH3NH2 to CH3NH3Cl required to create a buffer with pH of 10.26, I'm not sure where to start.

Answer 1

Start with the Henderson-Hasselbalch equation.
pH = pKa + log [(Base)/(Acid)]
10.26 = 10.64 + log[(base)/(acid)]
and solve for B/A.
You need to look up pKa for methylamine in your text. The number I have above I picked up from the Internet.