This thread is about the guideline for a character creation. Someone from the community ask me to. Please feel free to add some comments if I miss something. Enjoy!
For a character creation, you essentially need to define three things: Race, Background and Class.
There many different kind of humanoids in D&D you can play with. The most common are described in the PHB: Human, Elf, Half-Elf, Dwarf, Halfling, Gnome, Half-Orc, Dragonborn, Tiefling. Volo's Guide to Monster and the Elemental Evil supplement expand a little bit the playable races (Goliath, Genasi, Deep Gnome, Aacrakora, Firbolg, Lizardfolk, Triton, Asimar, Tabaxi...).
Generally, the selection of the one races gives some features to the character. Some features are common for each race, some varies according to the sub-race, if any. These feature always include some bonus (or malus) on the ability score (Strength, Dexterity.....), the size and longevity, general alignment trend. Other feature might be some proficiency on skills (like the proficiency on the Perception skill for elves), or regarding senses like darkvision. In any case, these features directly apply to your character.
The background are described in the PHB. The background described a kind of general backstory for you character. You can feel free to expand this backstory as much as you like. IN the PHB, once you select the background, the are also some guidelines for: PERSONALITY TRAITS, IDEALS, BONDS and FLAWS. These thing help you to role-play the character. Moreover, the backgrounds gives you generally some proficiency on skills and tools, in some cases a bonus language, starting equipment and a feature. This feature may be not strictly applicable to the statistics of your character, it is more about the roleplaying.
The class defines what you can do in the D&D world. Generally, at level 1 you choose a class. Later on at higher level, you have to select an archtype. For example, a fighter at 3rd level has to select an archtype between Champion, Battle-Master, Eldritch Knight. The class always adds your character with some features that are common with all the archtypes. These features goes from the amount of attacks you can do with one action, to the spellcasting ability of spellcaster. Other features are specific for each archtype. At higher levels you get more and more powerful features. Usually, in the PHB there is a table that summarise this.
Before or after selecting these three aspect of your character, you can roll 3d6 (best 3 out of 4) for each of your statistic (STR, DEX, CON, INT, WIS, CHA). You decide how to distribute the rolls to your stats. Example, if you choose to be a wizards, your highest stats roll must be put in INT.
Word of advice: Race, Background and Class are not isolated black-boxes. All three contemporarily define your character. Do not think too much about the mechanics, think about the kind of character you want to build to have fun.