I have an LG enV touch on the Verizon Network and I would like to block a certain number (my ex) from contacting me. I am not sure how to go about this.

Depending on your carrier you may or may not have this featuire but you do have other options. How to Block Cell Phone Caller ID (http://www.timeatlas.com/cell_phones/general/blocking_cell_phone_caller_id)

Thank you