Could someone help me with a good build for a paladin. Thanks and excuse my english

By build, I assume you mean Kit? The differences in kits are:

Inquisitor (like Keldorn):
Pros:
Immunity to Hold and Charm
Dispel Magic (speed 1) 1xDay per 4 levels
True Sight 1xDay per 4 levels

Cons:
Cannot Turn Undead
Cannot Lay On Hands
Cannot use priest spells

Undead Hunter
Pros:
Immunity to Hold and Level Drain
+3 THAC0 & damage vs Undead

Cons:
Cannot use Lay On Hands

Cavalier
Pros:
Immunity to Fear, Charm, morale failure and poison
20% resistance to Fire and Acid
+3 THAC0 & damage vs Demons and Dragons
Remove Fear 1xDay per level

Cons:
Cannot use any missile weapon, unless it has a melee component (Axes/Daggers)


Just remember that rolling for a Paladin is the most difficult roll of all of the classes, because it has no real dump stat. ALL stats, with the possible exception of INT are important, and even INT is important in BG2 (Mind Flayers).

The useless stat for paladins is wisdom, lower is as much as you can at creation.
The almost useless stat is int, lower it in favor of the others.
Try to get str, dex, con and cha to 18, excess points into int. If you don't get a good roll make sure at least 3 of those stats are 18.

All three kits are powerful. Inquisitor's drawback is the inability to cast priest spells, which DOES hurt in late game. It's more than compensated by an incredibly powerful Dispel Magic and a True Sight that has a very low casting speed. Inquisitors make dealing with mages (arguably the most powerful opponents in the vanilla game) very easy.

There are some good throwing daggers/axes in SoA, so the Cavalier's drawback isn't that important. Ranged weapons aren't nearly as deadly in BG2 as they are in BG1 anyway. Cavaliers are a very solid kit with no real drawbacks.

Undead Hunter: immunity to Hold and level drain is nice, but there are plenty of ways to avoid those conditions. Loss of Lay on Hands doesn't mean much. Solid, but unspectacular.

First time player? Go Inquisitor for a relatively easy time.

AS for stats: Set Wisdom to 13, which is the minimum requirement. Useless stat for paladins. Ideally strength should be 18/xx dex 18 and con 18. Try to get 11 intelligence to avoid being intelligence drained to death by Mind Flayers.

I wouldn't bother too much about mind flayers, it's just one monster type and they'll need to roll a natural 20 in order to hit you (unless you're paralyzed but in this case you're screwed anyway). 6 int will allow to survive one melee hit, 11 will allow to survive 2.

Strength(damage), dexterity(AC and ranged attacks) and con (hitpoints) on the other hand are useful in almost every battle including versus mind flayers.

A character with less than 9 int can't use scrolls but paladins can't use priest scrolls anyway and other party members can use scrolls which don't have class restrictions.

With regards to Mind Flayers, Potions of Genius take care of the brain-sucking ability, since they increase Int a fair bit. Just have some in your Tank's quick item slot and pay attention to the combat notifications. Buffing up with them, to Int 25 *before* face to tentacle combat never hurt either...