advice needed for the online selling data management

i have been working part time and have connection with suppliers who send me images in thousands with description data in excel, all i need to have them uploaded it some place and sorted so i can have them listed on multiple sites like amazon.not able to understand how to manage data and get easy downloading and uploading of the same

sorry if i am posting at thr wrong place but i was only able to find this site where i think i can ask for advice

thanks and sorry