There are a couple of ways, you can just copy and paste their username like this
Or you can go their profile, copy the URL, and past it into the message like this http://www.smogon.com/forums/member.php?u=116662
Or you can highlight text, the click on the insert link button, and copy the text into the inset link box
Tiers aregroupsings of pokemon to try to make it so that you can use different "levels" of pokemon.
So you dont have to use legendaries all the time
Uber are the highest, OU - overused next
UU - under used thrird,
RU rarely used the 4th,
and NU Neveru sed the fifth
Little cup is an entirely differnt tier, level 5 pokes with justthe first evolution
Little tier is the best
You can use lower level pokes in higher tiers, but not vice versa
And there are clauses, like sleep = you cant put more than poke to sleep at a time
Evasion, cant use moves that increase evasion.