I recently got my JAR PPL from the CAA in the UK, since I want to do my hourbuilding in the US I was looking for the forms and the process information to obtain my FAA PPL on the basis of my JAR PPL, according to what I know it's only paperwork, can anyone point me to the proper information?? I can't find it on the FAA page.

It is paper filling, plus a fee to the UK CAA and a visit to the Selected FSDO here in the US. So you need to know where you will be coming to fly before you fill it in (in order to specify the correct FSDO).

Once you get your temporary certificate from the FSDO (good for 120 days) , you will be required to complete a BFR to activate it to allow you to fly PIC in the US.
Te BFR is a minimum of 1 hour ground and 1 hour in the air - these are minimums but you should anticipate doing more than that as you have never flown in the US.
To prepare for your BFR - you should get:
a) a copy of the 2007 FAR/AIM
b) sectional and terminal charts - and fully understand them. Airspace is quite a bit different.

A BFR must be completed every 24 calendar months.

Some FSDO's also ask for a FAA Class 3 medical - even though this is not specifically asked for in the regs.

The US cert must be carried whilst flying and accompanied by your current JAA license at all times - plus a government issued photo id (Passport).

To get the ball rolling you have to complete a Certificate of Authenticity with the FAA.
They don't charge a fee for this but the UK CAA will charge you somewhere in the region of 38 pounds to divulge the information to the FAA .

The link to the FAA Cert of Auth is:
http://www.faa.gov/licenses_certificates/airmen_certification/foreign_license_verification/

At that link you will see various reference to 14 CFR etc -- these are all the regulations and documented in the FAR/AIM.

There is also a broken link to the UK CAA where you have to submit a form to them plus fee allowing them to divulge your records to the FAA.
The correct link at the CAA is:
http://www.caa.co.uk/docs/33/FORSRG1160.PDF

Here is a link to the UK CAA fee schedule (which I believe is still current)..
http://www.caa.co.uk/docs/175/srg_fcl_Scharges_ppl_06.pdf

Spot on SoCal.

My tupence worth is to get an FAA class 3 before you visit the FSDO in the states. Reason being is I was told I have to get one before they grant the certificate.

As SoCal has mentioned the regs do not specificaly say you have to. But if the issuing body tell you to then what choice do you have? It would be a shame to waste a trip for the sake of a medical certificate.