You might want to try: lichess.org/qa/29/whats-the-diference-between-im-nm-cm-lm-gm-and-fm
If that did not help and you did not understand it, these are the requirements for EACH title.
LM is a fun title exclusively used on lichess. It stands for Lichess Master. You have to be a good role model and ambassador of lichess and it is awarded rarely nowadays, but lichess has to gain your trust. You also have to be a good communal figure (no offensive arguments, swearing, etc.) and you also have to be a decent player. It is most commonly achieved by being a good ambassador to lichess and always being helpful and having a positive attitude towards the lichess community.
Candidate Master (CM) = 2200 FIDE rating or winning it in a tournament.
FIDE Master (FM)= 2300 FIDE rating or winning it in a tournament
International Master (IM) = 2400 FIDE + 3 IM norms (performing at or above 2499.5 or rounding up 2500) OR winning the title directly from a tournament. Please note that both of the requirements (rating + norms) must be met to achieve the IM title.
Grandmaster (GM) = 2500 FIDE + 3 GM norms (performing at or above 2599.5 or rounding up 2600) OR winning the title directly from a tournament. Please note that both of the requirements (rating + norms) must be met to achieve the GM title.