I want to obtain some work experience information about sharepoint server.Shall I install trail version of Sharepoint on my machine ?If trail version is allowed ,where is the point do i really need to start?
SharePoint 2007 requires Windows Server, but SharePoint 2010 can be installed on Windows Vista and 7.
In my opinion, these 2 books are excellent as starting point:
You can use the free version of Sharepoint. This is Windows SharePoint Services 2007 or SharePoint Foundation 2010. If you are new to SharePoint then you would be better off using the new 2010 version. This is still in beta but should be released really soon.
As pointed out by Timores, you can install this on Win 7 or Vista but if you plan to do development for customers then you should use a server platform like 2008 R2.
Assuming you are a complete newbie to SharePoint, you should spend quite a lot of time learning the platform and architecture. There are many great books and web sites you can refer to.
After that, the sky is the limit. It really depends what you want to do with the platform.
MOSS 2007 / SharePoint Enterprise 2010 is a very large, very complex beast. If you feel happy/bored with WSS/Foundation then give the full product a try.
For me, it's taken 2 years to feel confident with SharePoint development. I fought the beast for a year but now we have arrived at a comfortable standoff. :)