general way to upload a file is the way from your computer to their hosts, which is slowly and easy to cause a problem and the process shut down.
another way to upload is remote way. you find the real link of the file and put the link then the process will work and it will take a short time. however there are fewer and fewer files we can find that show a real link to the visitors, so we should try another way.
the way is by using vps. however it is not free to use vps. to buy a cheapest vps service, it may cost about $5 to $8 per month. you can choose windows or linux system but mostly people choose windows which is a little expensive than linux. when all is setup, you could download files in the host and upload the files you have downloaded to the programs you have joined, currently one of the most popular is filesonic, others like wupload is also hot now.
so the third way is a professional way for you, make effort and you will surely make profit. but you should know some more tips such as pay per download and pay per sale in those programs.
you can read these article for more details.