If you think about normal jump from ropes you need to go near corner of ring, press L + O buttons, so he will climb it, and then any of attack buttons for jump.
But you probably think about something special, what only Eddie does, for that you need only to play as Eddie, or have his moveset, if you play as custom character

To do a jump attack like eddie guerrero you first have to select him in the move set option whem making a superstar then climb the turnbuckle using L+O then press any of the action buttons. Triangle is the most powerful jump attack.

chegas ao pe do canto com o guerrero carregas L+O e fazes o finisher