Auto snap and loop consturction not working

I'm assuming that you mean Loop Button and Audio Snap. 

When you have the Loop Construction view open Press F1 - that will open the Help file to the information you need to understand what's going on.
 
YOu can audition loops from the Browser but to do anything else you need to drag them onto a track. Then when you double click the loop it will open in Loop construction view where you will be able to edit it according to the parameters available. That view is for editing the looping properties not the audio properties. Do that in track view.
Any way it sounds like you need to read up on it. SONAR's help files are very comprehensive.

the same for Audio Snap - Read up on it before asking moire questions. Not all clips can be acted on by Audio Snap. EXAMPLE. groove clips wont respond to Audio Snap. You need to create an ordinary audio clip first. Again, open the Audio Snap Palette form the Views Menu and Press F1 to open up the associated Help file. Its the same information as presented in the SONAR reference Manual which is supplied with SONAR, either on the Discs or the download version. It's also available from the Cakewalk website.