I have looked for days on how to be a combatant in the arena in morrowind...can someone please explain to me?

You can't, not without a mod. The arena in Vivec is purely for special duels between nobles apparently. You can fight in the arena, only you have to piss off the right people first.

thanks jack!

If you play on PC you can use the mod "To the Death" by Fliggerty to challenge almost any NPC to a duel in the Arena. It requires Morrowind Script Extender, and I think that it is perhaps a touch buggy (slightly), but it can be fun.

Sounds like a mod I might want to check out. I've got good memories of the arena.

Such as challenging Darius with a rather low level character. I was so nervous I drank a ton of Flin, brandy and potions before the match. My strength topped at over 700. Needless to say, the battle was over after three strokes.(the first one missed.)

and how do i get this mod?
lol

It's called "To the Death". You should be able to find it on Planet Elder Scrolls or, failing that, Fliggerty's Morrowind Mods Page. Easy enough to find via Google search.

It also requires Morrowind Script Extender, which can also be found on Fliggerty's site.

Sounds like a great mod. I would check it out but you said that the game can start lag and that's the least thing I want to happen. I got so mad when Oblivion started to lag on my computer so now I play on the 360.
But it really sounds like a great mod.