We have access to core books only , including ph2. I have heard that since healing surges exist , a cleric is not that useful. However i may be wrong.
Well, there are limited means to trigger healing surges.
Sure, if you make it through combat, a short rest will heal you up ...
During combat, however, most characters (at low levels) only have their second wind, and using that is usually a standard action (which could be better used taking down foes).
Also, consider that rogues and wizards have low hit points and low surges per day.
A wizard with 24 hp will have a surge value of 6 ... if a cleric uses healing word, they'll heal an additional D6+cleric's wis modifier (due to healer's lore), effectively doubling what each surge is worth.
And healing word is a minor action, so the cleric can attack on the same turn.
Would just like to point out that without healing bonuses, if a rogue or wizard falls unconscious 2 fights in a row, they'd be out of surges.
Having said all that, however ... I'm from the school of "healing is just delaying losing" where overwhelming offense can substitute for healing ('cos dead foes can't hurt you).
At the end of the day, it comes down to play style (and how deadly the group is).
Sample laser ('cos it shoots beams of light) cleric.
Human cleric:
Str 8, Con 11, Dex 13, Int 10, Wis 18, Cha 16
Improves Wisdom and Charisma every stat bump.
Feats: Implement Expertise - Holy Symbol (PH2), Distant Advantage (PH2)
Powers: Lance of Faith, Sacred Flame, Divine Glow, Beacon of Hope
If the fighter and rogue are trying to flank all the time, you'll get combat advantage too.
With a high hitroll on Sacred Flame, you should be able to keep everyone in good health (temp hp and/or saving throws).
Divine Glow is versatile, it's both multi-target damage and a hitroll bonus for allies in the blast.
Consider picking up Astral Fire soon (as well as a magic holy symbol) to increase damage output.
Warrior of the Wild is also a good feat to take (two rounds of bonus damage is nice, but training in perception pure awesome).