not letting me download on my iphone 4

this is my first iphone ever :) & very pleased with the phone, however im wanting to download ring tones & im getting to these apps tht supposable lets u make your own... ive been referered to upgrading to two different apps & yet have been able to download a ring tone... i wonder if im doing something? i have a iphone 4 then these apps are saying they work for my phone but then says i need to up grade. there i go spending another dollar... can someone please tell me what im doing wrong cause im getting tired of purchasing & not getting what im paying for...

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