In theory the SPI module should be rather easy and straight forward if you're not going to use any advanced features.
Make sure (SPIxCON1):
You're not using both primary & secondary prescale 1:1. For example, set one to 1:2 or 1:4, and the other to 1:1 (if you really need the high clock speed).
Enable master mode (bit 5 = 1)
Select your clock settings (bit 6 and 8 ). You should see some clocks I think, but if they are set wrong you may lose your first or last bit.
I would set data sampling at middle if your clock speed allows it
Make sure you enable the SDO and SCK.
SPIxCON2 is all for FIFO and SPI framing. Set it to 0 if you don't use it Make sure to read the errata if you do want to use that, some early PIC24 parts had some horrible FIFO bugs.
When transmitting just poll the SPIxSTAT.SPIRBF bit until it goes high, then the transfer should be done.
SPIxSTAT.SPIEN (bit 15) should be set to 1 to enable the module. Make sure to reset the module before configuring it, you can't first enable the module and then change registers. In my projects I reset all registers to 0 (CON1, CON2, STAT), write my settings, and then enable the module.
That's about it as far as I can see. It seems like the PIC24FJ128GA006 does not have PPS, so that's one less module to worry about.
If you do have all of this, then feel free to post your code. Otherwise we can only guess (like this post is all about).