Marketing means not only selling product to customers but even though the seller hasn't have a product. He can sell. Most of the customers never try to buy products from internet. But most of then try to buy softwares, games from internet. It is easy to sell softwares and other apps through internet than selling things because the seller didn't need a transport facilities to transport product and he/she don't want to aware about the warranty and other safety of the product. If a sold product some times may get damage so the seller has to repay or change the product. But in the case of selling apps it will not go like that. The seller need only some payment processors and a contact line.
Tips to sell softwares
You have to own a personal website. If you are software developer you can create your own software and sell it or you can promote apps from other sites. If you are selling other members product you will only get its commision.
Step1: Create a new webpage and add the details and picture of the product. If you are promoting other sellers product add your referral id.
Step2: Make 2 or 3 payment processor like paypal, payza, skrill etc for to receive cash. If you are not the owner of the product no need of this.
Step3: Add a demo version of the software. In order to know the benefits of the apps to customers adding a demo version is important.
Step4: Make traffic to your website. If there is no visitors it is not easy to get customers. Make use of the social medias and advertisement options.
After this you will earn from the sells of the apps. Provide a contact email or phone information in below of the product. When you add the price of the product don't try to add more price. Add only the cost of the product if the price of the product is too high no one buy your product. Only an imaginable price get buyers. All the best.