[R] lme4 / HLM question

[Jeff]

   I'm hoping that this is a relatively easy question for someone familiar with
   the lme4 package.
   I'm accustomed to using HLM software and writing a simple 2 level [null]
   equation like this:
   L1 - Yij = b0 +  e
   L2 - b0 = B00 + u0
   The following command in R provides results that are identical to the HLM
   program.
   results <- lmer( Y ~ 1 |id , PanelData4)
   I can't seem to find any examples on-line nor in the help about how to write
   the lmer4 formula that contains two predictor variables at level 1 with
   fixed slopes.
   L1 - Yij = b0 + b1(x) + b2(z) + e
   L2 - b0 = B00 + u0
          b1 =  B10
           b2 = B20
   Can someone give me an example?
   Thanks
   Jeff