[TYPO3-english] How can i hide my records from specific categories in my extension

[F a]

I am some how new with typo3, I have created an extension, I want the user to be able to choose records from which categories should be shown in front end, for this i have created a setting from in flexform, did the necessary setting from TCA to allow editor to choose which category an article belongs to. 
Now my question is how can i make my extension so that it only shows records that editors set through my extension setting. 
Thanks in advance