How to create filter in PowerApps?

I have an App that is connected to a SharePoint document library and I'm trying to make the app so that users can use a filter for the document tags. 

The OnSelect code for the top filter is: 
Filter(DocLibraryName, (JobRole.Value = Doc_ComboBox_JobRole.Selected.Value || IsBlank(Doc_ComboBox_JobRole.Selected.Value)))

The Items code for the Gallery is: 
Filter(DocLibraryName, (!IsBlank(Name) && !IsBlank(JobRole) && !IsBlank(SegmentProcess)))