Before writing a script, or any code, you must have an algorithm. An algorithm is a word picture of what the script has to do.

Start with a simple question: How do I turn Sheet Tabs red if that Sheets Range("B3") is larger than 42?

The algorithm:
Look at each sheet
Compare Range("B") to 42
IF it is LARGER than 42 THEN
Turn that sheet tab red

Declare a routine, or Script, or Sub 
Sub RedTabs()
'(I see that) we need a variable to hold each sheet while we work with it.
Dim Sht As WorkSheet

For Each Sht in Sheets 'look at each sheet
If Sht.Range("B3") > 42 Then
Sht.Tab.Color = Red 'Tab is an Object and Color is a Property
Next 'Look at the next Sheet in the Collection.
End Sub
.

The beauty of a Basic Language like VBA or NaturallySpeaking is that the actual code very closely resembles the algorithm. The problem is that you must first understand enough to ask a suitable Simple Question.

I await your return in a few days.