  These are notes for four lectures given at the 2010 CIMPA Research School
"Automorphic Forms and L-functions" in Weihai, China. The lectures focused on a
Burgess-like subconvex bound for twisted Hilbert modular L-functions published
jointly with Valentin Blomer in the same year. They discussed the proof in some
detail, especially how spectral theory can be used to estimate the relevant
shifted convolution sums efficiently. They also discussed briefly an
application for the number of representations by a totally positive ternary
quadratic form over a totally real number field.
