# the founder and perfecter of the faith

"creator and finisher of our faith" or "the one who enables us to have faith from beginning to end"

# For the joy that was placed before him

The joy that Jesus would experience is spoken of as if God the Father had placed it before him as a goal to reach. 

# despised its shame

This means he was not concerned about the shame of dying on a cross.

# sat down at the right hand of the throne of God

"sat down at the place of honor and authority beside the throne of God"