You can upload your products to Shop from the Catalog > Products section, select all the products or only those you need, click on More > Publish in Shop.
.Another option is to access the product tab > Shop tab, click on Edit within the tab and check the Post to Shop checkbox.
You can also do it massively via an update from Settings > Import/Export > Update from file, indicating in information type "Shop Products" and in the "Show Shop" field indicate Yes.