How to loop through range of cells in Excel VBA?

I am trying to use a For LOOP to alternate throught the range of cells in Excell but do not quite remember the syntex.   Here is what i am trying to do:  

On row 1 select first three cells (for example:  A1, B1, C1) and do something with it.  
Then next loop around should select next three cells on Row 1 (example:  D1, E1, F1)  and do somthing with it
Then next loop around should select next three cells on Row 1 (for example: G1, H1, I1) and do something with it.

I sort of started this but do not quite know how to alternate through Range("?1:?1")

For K = 1 To  30
    Range("?1:?3").Select
    Selection.Merge
    ActiveCell.FormulaR1C1 = "Question" & K
 Next K
 
In the place of questions mark not sure what to put...

Any help is appreciated.