First of all go through Declarative then go for VF and Apex https://developer.salesforce.com/page/Force_Platform_Fundamentals http://www.salesforce.com/us/developer/docs/pages/salesforce_pages_developers_guide.pdf https://www.salesforce.com/us/developer/docs/apexcode/index_Left.htm#CSHID=langCon_apex_primitives.htm|StartTopic=Content%2FlangCon_apex_primitives.htm|SkinName=webhelp
What is your end requirement? You can always use a 3rd party service like dbsync to integrate Salesforce with Quickbooks. If you want to do that, follow the steps listed here - http://help.mydbsync.com/docs/display/dbsync/Salesforce+QuickBooks+Integration+with+Multiple+QuickBooks
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https://developer.salesforce.com/page/Force_Platform_Fundamentals
http://www.salesforce.com/us/developer/docs/pages/salesforce_pages_developers_guide.pdf
https://www.salesforce.com/us/developer/docs/apexcode/index_Left.htm#CSHID=langCon_apex_primitives.htm|StartTopic=Content%2FlangCon_apex_primitives.htm|SkinName=webhelp
If my answer helps resolve your query, please mark it as the 'Best Answer' & upvote it to benefit others and improve the overall quality of Discussion Forums.
Gaurav Kheterpal
Certified Force.com Developer| Salesforce Mobile Evangelist| Developer Forums Moderator| Dreamforce Speaker