Easy-Peasy nowadays.
Firstly, TAKE YOUR TIME.
Usual culprits for first timers are making sure you use the correct stand-offs when fixing the motherboard to the case (i.e don't bolt the motherboard directly to the case), don't forget to use either the TIM (thermal interface material) that comes on the heatsink or clean off and replace with something similar, make sure the front panel connectors (power, reset etc) are plugged in correctly, if the GPU requires additional power plug it in and don't forget the 12v motherboard connector. The RAM will only go in one way, check the locating lug-hole on the connector side of the modules
Most things only go in one slot. It's difficult to get it wrong
Good luck with it. Come back if it all goes horribly wrong.
