So, now that your back, we should have a refresher course.
ABCDEFGHIJKLMNOPQRSTUVWXYZ - These are capitals. They go at the beginning of sentences and the first letter of a pronoun.
abcdefghijklmnopqrstuvwxyz - These are lower case. You can use these for all the other letters.
.!? - These are puncuation marks. They go at the end of sentences.
Ha, just giving you some grief to welcome you back. Tell us how work was.