i'm a newbie in terms of apex programming. Where i not very sure how write a test class, with 75% coverage.
as your question relates to writing code, you should first go to developer.salesforce.com and look for further information on how to write testclasses. Test classes have been a mandatory part of code deployment in Salesforce to ensure that the code being deployed does not cause errors when it is run. The first thing to do is read this section: Testing Custom Controllers
The next step is to head over to the Force.com's Developers User Guide and read the section on Testing Apex.
Lastly, read this about code coverage: Code Coverage Best practices
Once you have started writing your test class and run into problems you can then post your issue with sample code here.