DIY stickers

So I am going to attempt to make my own mongram stickers. I know some of you made your own and they came out awesome. What programs did you use? I have a MAC.

TIA

I bought round stickers for candies at Michaels (the kind you stick to the bottom of hershey kisses). There is a website to download a template from. I printed our monogram on them. There are 216 stickers in a package and with a 50% off coupon they were about $3

ETA oh I am using them to close my pocketfolds :)