The datasheet seems pretty thorough, and the core functionality looks pretty straightforward. Once everything is set up, you clock in RGB values one pixel at a time. First you go across a row, then down a column.The relevant control signals are:
DR[7:0] - 8-bit red value for the current pixel
DG[7:0] - 8-bit green value for the current pixel
DB[7:0] - 8-bit blue value for the current pixel
DCLK - When this goes high, the pixel data is latched. When it goes low, the LCD switches to the next horizontal pixel
DE - When this is high, pixel data can be latched. I think when it goes low the LCD switches to the next row, but I'm not sure whether it's independent of DCLK.
U/D - Selects whether to go up or down a row when DE toggles
R/L - Selects whether to go left or right a pixel when DCLK toggles
So the basic flow will be (from the start of the first row)
Initial conditions: DE=1, DCLK=0
Step 1: Set the RGB values for the pixel via DR, DG, and DB.
Step 2: Drive DCLK high to latch the RGB values.
Step 3: Drive DCLK low to select the next pixel in the row.
Step 4: Repeat steps 1-3 800 times total to set every pixel in the row.
Step 5: Drive DE low to select the next row.
Step 6: Drive DE high to enable pixel writes.
Step 7: Repeat steps 1-6 600 times total to cover every row.
There are lots of timing constraints on these steps. Section 5 has the specs for those.
There are some other control signals, voltage references, and a serial interface. I'm not sure what the serial interface is for, but I didn't look very thoroughly. None of them looks terribly complicated.
All that being said, using this LCD will be very difficult. This is a complex mixed-signal system. Plus, as described in section 4a, you need six separate voltage supplies. There are some example schematics for switching regulators in section G, but each of those is a project in itself.
Studying the datasheet could be very educational, but I don't recommend this as a project for a beginner.