Car won't start - I think the carburetor needs to be cleaned.

My car will not start. When I attempt to turn it on, it tries to start but doesn't get there. The starter was replaced about three months ago. The battery is new and all the electrical components come on. The spark plugs spark. My friend attempted to fuel inject it but it still did not start. My friend, who has basic knowledge about cars, said that the carburetor may need to be cleaned. I bought the supplies and did a lot of research but most of the research said to use the carburetor cleaner while the car was running. Well, my car will not start so I did not want to try that and make the problem worse. Please help.