I had zero experience with AR's when I purchased the parts and built my first one. The hardest part for me was being overwhelmed at all the parts and trying to understand what to buy. The assembly is not that complicated if you are at all handy with basic tools. Plenty of YouTube videos out there to follow.

There are numerous ways to achieve a completed gun, from buying parts kits that include everything you need down to buying every single individual part separately. For your first one, i'd recommend using kits. It'll help you make sure you have everything you need, and once you see how it all goes together then you can get more adventurous on the next build. Summary below on the basic parts you need, will include a link to an example of each one.

Lower - Option 1
1) Stripped Lower Receiver (Requires FFL Transfer) LINK
2) Lower Build Kit (Typically includes every part you need to assemble the lower) LINK

Lower - Option 2
1) Stripped Lower Receiver (Requires FFL Transfer) LINK
2) Lower Parts Kit LINK
3) Stock & Buffer Tube Kit LINK

Lower - Option 3
1) Stripped Lower Receiver (Requires FFL Transfer) LINK
2) Lower Parts Kit Without Fire Control Group LINK
3) Trigger Set/Trigger Group/Fire Control Group LINK
4) Stock & Buffer Tube Kit LINK

Upper
1) Stripped Upper Receiver (With or Without Forward Assist) LINK
2) Ejection Port Cover Assembly LINK
3) Forward Assist Assembly (Depending on item 1) LINK
4) Bolt Carrier Group LINK
5) Charging Handle LINK
6) Barrel (Can't go wrong with a 16" barrel, anything shorter read up on laws regarding Short Barrel Rifles vs Pistols. Also read up on gas systems for which ever barrel length you choose.) LINK
7) Barrel Nut (Some free float rails item 8 require specific barrel nuts to mount them) LINK
8) Free Float Rail (Recommend m-lok style, length dependent on barrel length and visual preference) LINK
9) Muzzle Device (flash hider, muzzle brake, etc. make sure the thread size matches your barrel) LINK
10) Gas Tube (make sure it matches the gas system your barrel is designed for I.E. Pistol, Carbine, Mid-Length, Rifle) LINK
11) Gas Block (make sure it matches the gas block diameter on your barrel, and that it will fit under your free float rail) LINK

For tools i'd recommend the following:
1) Armorer's Wrench LINK
2) Roll Pin Punch Set
3) Upper Receiver Vice Block (You can get away without a lower receiver vice block) LINK
4) Vice
5) Torque Wrench
6) Pivot Pin Tool (Not required but highly recommend) LINK

Hope i'm not forgetting anything here, and hope this simplifies what you need to buy. If you have any questions on what parts to buy, just ask them here. There's nothing I enjoy more than shopping for AR-15 parts with other people's money