The young man (has been a) League member (for) two years.
Two years (has passed),(since) the young man (has joined the) League.
The young man (has been in the) League (since) two years ago.
It is two years (since) the young man (has joined) the League.
这样填应该没错,有什么问题请追问 、
希望及时采纳—— ♥ 多谢 ⌒_⌒