03 Z400 sport quad transmission problems HELP!

Ok here is the deal.. I have an 03 suzuki z400 that is not going into gear.  When I depress the shift lever it feels as though it is moving into gear but when pushed forward it moves freely as if still in neutral.

My questions   ..  where do I start to try and diagnose this problem.  Second, Is this something that someone with limited mechanical abilities could fix.

I have only worked on two strokes so far..  they seem to be fairly easy and simple but I understand that four strokes are much different.  

If anyone has experienced this problem and can pinpoint it right away for me that would be great.  I am obviously thinking that the clutch isn't engaging but I should still be able to hard shift it and it go in gear right/?  Any help would be appreciated thanks so much.  craig  

I have a 06 and it had the same problem a few yaers back, We took it to our mechanic and he said that there was a spring that engages the gears to switch that had snapped, check for the broken spring and replace, It ended up costing us about 50 bucks with labor included.