Modify a Flyer Template that is in .eps file format (also have one in .ai format if that works better)

Hi, I have purchased a template for a flyer that I would like to customize. We would like to save 2 flyers. The flyer is in .eps format and has been attached. We are looking to make a few modifications.

Instead of saying "Softball League", we want it to say "GIrls Softball"
Instead of Saying "Register December 1", we want it to say "Register Now at DHYS.org"
On the left hand side, we would like to add
Girls Leagues: (this line should be underlined)
6U/8U (centered below the underlined "Girls Leagues")
10U (centered below the underlined "Girls Leagues")
12U (centered below the underlined "Girls Leagues")

On the Softball, we want the words centered "DHYS.org"

For the second one, we are going to have everything the same, except, the language on the left hand side. We will use this modification:
On the left hand side, we would like to add
Girls Leagues: (this line should be underlined)
6U (centered below the underlined "Girls Leagues")
8U (centered below the underlined "Girls Leagues")
10U (centered below the underlined "Girls Leagues")
12U (centered below the underlined "Girls Leagues")

I have to run the final document past my superiors to see if they ask for any modfications, but anything we ask for will be very minor.