I have enough exposure in force.com and now I want to learn Salesforce CRM.
How can I start on this?
Is there any guide available for this?
I recommend Trailhead as the first resource for all help. Sign up using trailhead.salesforce.com
Apart from that Salesforce help and training portal has all the great info
https://help.salesforce.com/apex/HTViewHelpDoc?id=salesforce_help_map.htm&language=en_US
Apart from this, Salesforce has implementation guides in both PDF and html formats.
You can refer these, they are excellent for hands on.
In addition to the excellent help and implementation guides @Mohith pointed out there is a lot of other online content.
The Salesforce online training has a selction of great online training courses. You can see some of the trainings directly on the help page (lower left corner). The Implementation Expert certification study guides list out the courses that are helpful for implementing Sales Cloud, and there are many, but your access to the various courses may depend on your relationship with Salesforce (partner, customer, etc.).
There are many very good Youtube sessions put out by Salesforce. You can find many linked to from:
The Youtube demos by Alex Zarowny give quick (~15 mins), but thorough introductions to various areas of Salesforce from a user perspective. They are a little bit older, but still relevant and very well done. For example:
I recommend Trailhead. There you can find many modules, trails and even projects regarding Salesforce CRM. Trailhead is made by Salesforce and is my favorite learning platform.
My suggestion would be to start with CRM essentials trail and then proceed with Admin Beginner, Admin Intermediate and Admin Advanced.
Salesforce docs has many good guides. You can either download them as PDF or view online.