How do I get a Sharingan?
The Sharingan can be evolved into the Mangekyō Sharingan by experiencing the trauma of loss, granting unique, user-specific jutsu in addition to the Sharingan’s standard abilities. Awakening the Mangekyō Sharingan will automatically fully mature a Sharingan if it isn’t already.
Can anyone use the Sharingan?
If you mean into himself then utilize it, yes. Technically speaking he can implant a sharingan/dojutsu into anyone, but the user must have the stamina required to utilize the dojutsu, so putting it into someone such as Gai or Lee would be useless (No offence to any Gai or Lee fans but their chakra just isn’t there).