Noob questions and suggestions

So I'm having trouble using the items section I've found that newly added items to my recommended items list don't appear in the correct spots.
Also I don't know how multiple item builds for the How does experience work does it only work if you get the killing blow? or just if your in the vicinity?
how do you know when you got an assist? Garens Demancian justice how do I know which player is the villain other than Other than red means damaging zone is there anything else that we need know? sparkling stars etc anyone want to link me to a new players guide? When playing random please write what the characters role is and list abilities. Please change description of what AR URF game mode is 3 lanes and is not a "ultra rapid" mode slower than twisted treeline