The build itself is straight forward, all the designators are clearly marked on PCB and there is plenty of room to maneuver around.
Install U1U and components around it, as well as J5U, diodes and resistor as shown above.
NOTE: make sure to install ferite bead FB1U (not shown on the picture above)
Your uC is now ready for boot load.
If you really want to install just the essential components to get the uC ready for loading boot file then install only uC, crystal, C18 and C19, D1, D2, C20 and C10, Resistors R3U and R1U, connector J5U, LED diode LD2U and FB1U ferrite bead. You are now ready to move to next phase.