Can any one tell me how to get rid of valve noise do i just tighten the rocker arm ?

 

You need to add detail to your post.

 

If valve lash is noisy yes, but you have to know how much. need feeler gauges and specs.

 

As I understand it, there is no adjustment for valve lash on the 3.8L engines; the lifters are hydraulic. If you have removed the rocker arm assembly, you need to make sure all the pushrods are correctly seated into the lifters, and the rocker arms are all properly aligned with the appropriate pushrods. Put a dab of oil on each end of each pushrod before installing them.
There is no bolt sequence specified in the Haynes manual I have, but I start at the center bolt and work outward. As a general rule, the hydraulic lifter assembly bolts should be tightened to 105 inch-pounds of torque in several stages, say 60 in-lbs, 90 in-lbs and then the full torque of 105 in-lbs. Make sure the pushrods are seated properly BEFORE continuing!
NOTE: You cannot use a torque wrench rated in foot-pounds for this! ONE ft-lb is equal to 12 inch-lbs, so 105 in-lbs is slightly more than 8 ft-lbs of torque, and even click-type torque wrench settings usually begin at 20 ft-lbs.

 

To your original question, if you have lifter noise, there are several possible causes. You may have a collapsed lifter, worn camshaft, or low oil level, viscosity or pressure, or a combination of factors. If the oil pressure light is not on, check your oil level, if it's ok, change the oil and filter, with a good quality oil. Since my engine has 200,000 miles on it, I use Castrol High-Mileage oil, which has a synthetic component added to it.
If your lifter noise continues after that, then you've either got a collapsed lifter or a worn camshaft, or both. You can find the noisy lifter with a mechanic's stethoscope, which may involve taking the valve cover off and running the engine briefly. If you need to run the engine with a valve cover off, you'll want to fabricate an oil dam to attach to the lower edge of the head to keep the oil from running onto the exhaust manifold and choking you with oil smoke.
A good shop manual for your make and model will help you with the correct procedures for replacing a collapsed lifter, and you'll likely need a lifter removal tool. DO NOT PRY on the lifter!

Hope that helps.