Get the service manual, and go through it step by step. This has also been covered quite a few times before, you might want want to look at older posts.
- the bike needs 3 things to start, fuel, spark and compression.
- If it sputters, starts, more likely to be a fuel problem / check carburettor, look at other posts
- if you dont hear the engine turning, its related to the starter. If there's no spark, its probably electrical.