# For we have the prophetic word made more certain

"For the things that we saw make this prophetic message more sure". This refers to the Old Testament. Alternate translation: "the scriptures, which the prophets spoke, made" 

# to which you would do well to pay attention

Peter instructs the believers to pay close attention to the prophetic message.

# as to a lamp shining in a dark place until the day dawns

Peter compares the prophetic word to a lamp that gives light in the dark until light comes in the morning. The coming of morning is a reference to Christ's coming.

# the morning star rises in your hearts

"Christ shines his light into your hearts like the morning star shines its light into the world"