HELP were do I put cost of materials

On page 2 of your Schedule C, under Cost of Goods Sold, Line 36 is called Purchases.  It is for all the things you buy for re-sale but you don't track it as Inventory.  Or, depending on how you view those items, you could enter them on line 38 as Materials and Supplies. 

Yes put the materials under Supplies.  

Supplies are the stuff used up in getting the work done or stuff turned over to the client. COGS is inventory. Stuff on shelves sold to buyers i.e. Corn Flakes in a supermarket.